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| <article role="main" id="furo-main-content"> |
| <section id="c-data-interface"> |
| <h1>C Data Interface<a class="headerlink" href="#c-data-interface" title="Link to this heading">¶</a></h1> |
| <p>Arrow supports exchanging data without copying or serialization within the same process |
| through <a class="reference external" href="https://arrow.apache.org/docs/format/CDataInterface.html#c-data-interface" title="(in Apache Arrow v19.0.0)"><span>The Arrow C data interface</span></a>, even between different language runtimes.</p> |
| <section id="java-to-python"> |
| <h2>Java to Python<a class="headerlink" href="#java-to-python" title="Link to this heading">¶</a></h2> |
| <p>See <a class="reference external" href="https://arrow.apache.org/docs/python/integration/python_java.html" title="(in Apache Arrow v19.0.0)"><span>Integrating PyArrow with Java</span></a> to implement Java to |
| Python communication using the C Data Interface.</p> |
| </section> |
| <section id="java-to-c"> |
| <h2>Java to C++<a class="headerlink" href="#java-to-c" title="Link to this heading">¶</a></h2> |
| <p>See <a class="reference external" href="https://arrow.apache.org/docs/developers/cpp/building.html" title="(in Apache Arrow v19.0.0)"><span>Building Arrow C++</span></a> to build the Arrow C++ libraries:</p> |
| <div class="highlight-shell notranslate"><div class="highlight"><pre><span></span>$<span class="w"> </span>git<span class="w"> </span>clone<span class="w"> </span>https://github.com/apache/arrow.git |
| $<span class="w"> </span><span class="nb">cd</span><span class="w"> </span>arrow/cpp |
| $<span class="w"> </span>mkdir<span class="w"> </span>build<span class="w"> </span><span class="c1"># from inside the `cpp` subdirectory</span> |
| $<span class="w"> </span><span class="nb">cd</span><span class="w"> </span>build |
| $<span class="w"> </span>cmake<span class="w"> </span>..<span class="w"> </span>--preset<span class="w"> </span>ninja-debug-minimal |
| $<span class="w"> </span>cmake<span class="w"> </span>--build<span class="w"> </span>. |
| $<span class="w"> </span>tree<span class="w"> </span>debug/ |
| debug/ |
| ├──<span class="w"> </span>libarrow.800.0.0.dylib |
| ├──<span class="w"> </span>libarrow.800.dylib<span class="w"> </span>-><span class="w"> </span>libarrow.800.0.0.dylib |
| └──<span class="w"> </span>libarrow.dylib<span class="w"> </span>-><span class="w"> </span>libarrow.800.dylib |
| </pre></div> |
| </div> |
| <section id="share-an-int64-array-from-c-to-java"> |
| <h3>Share an Int64 array from C++ to Java<a class="headerlink" href="#share-an-int64-array-from-c-to-java" title="Link to this heading">¶</a></h3> |
| <p><strong>C++ Side</strong></p> |
| <p>Implement a function in CDataCppBridge.h that exports an array via the C Data Interface:</p> |
| <div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><iostream></span> |
| <span class="cp">#include</span><span class="w"> </span><span class="cpf"><arrow/api.h></span> |
| <span class="cp">#include</span><span class="w"> </span><span class="cpf"><arrow/c/bridge.h></span> |
| |
| <span class="kt">void</span><span class="w"> </span><span class="nf">FillInt64Array</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="kt">uintptr_t</span><span class="w"> </span><span class="n">c_schema_ptr</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="kt">uintptr_t</span><span class="w"> </span><span class="n">c_array_ptr</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">Int64Builder</span><span class="w"> </span><span class="n">builder</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">builder</span><span class="p">.</span><span class="n">Append</span><span class="p">(</span><span class="mi">1</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">builder</span><span class="p">.</span><span class="n">Append</span><span class="p">(</span><span class="mi">2</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">builder</span><span class="p">.</span><span class="n">Append</span><span class="p">(</span><span class="mi">3</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">builder</span><span class="p">.</span><span class="n">AppendNull</span><span class="p">();</span> |
| <span class="w"> </span><span class="n">builder</span><span class="p">.</span><span class="n">Append</span><span class="p">(</span><span class="mi">5</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">builder</span><span class="p">.</span><span class="n">Append</span><span class="p">(</span><span class="mi">6</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">builder</span><span class="p">.</span><span class="n">Append</span><span class="p">(</span><span class="mi">7</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">builder</span><span class="p">.</span><span class="n">Append</span><span class="p">(</span><span class="mi">8</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">builder</span><span class="p">.</span><span class="n">Append</span><span class="p">(</span><span class="mi">9</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">builder</span><span class="p">.</span><span class="n">Append</span><span class="p">(</span><span class="mi">10</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Array</span><span class="o">></span><span class="w"> </span><span class="n">array</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">*</span><span class="n">builder</span><span class="p">.</span><span class="n">Finish</span><span class="p">();</span> |
| |
| <span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">ArrowSchema</span><span class="o">*</span><span class="w"> </span><span class="n">c_schema</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">reinterpret_cast</span><span class="o"><</span><span class="k">struct</span><span class="w"> </span><span class="nc">ArrowSchema</span><span class="o">*></span><span class="p">(</span><span class="n">c_schema_ptr</span><span class="p">);</span> |
| <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">c_schema_status</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">ExportType</span><span class="p">(</span><span class="o">*</span><span class="n">array</span><span class="o">-></span><span class="n">type</span><span class="p">(),</span><span class="w"> </span><span class="n">c_schema</span><span class="p">);</span> |
| <span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="o">!</span><span class="n">c_schema_status</span><span class="p">.</span><span class="n">ok</span><span class="p">())</span><span class="w"> </span><span class="n">c_schema_status</span><span class="p">.</span><span class="n">Abort</span><span class="p">();</span> |
| |
| <span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">ArrowArray</span><span class="o">*</span><span class="w"> </span><span class="n">c_array</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">reinterpret_cast</span><span class="o"><</span><span class="k">struct</span><span class="w"> </span><span class="nc">ArrowArray</span><span class="o">*></span><span class="p">(</span><span class="n">c_array_ptr</span><span class="p">);</span> |
| <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">c_array_status</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">ExportArray</span><span class="p">(</span><span class="o">*</span><span class="n">array</span><span class="p">,</span><span class="w"> </span><span class="n">c_array</span><span class="p">);</span> |
| <span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="o">!</span><span class="n">c_array_status</span><span class="p">.</span><span class="n">ok</span><span class="p">())</span><span class="w"> </span><span class="n">c_array_status</span><span class="p">.</span><span class="n">Abort</span><span class="p">();</span> |
| <span class="p">}</span> |
| </pre></div> |
| </div> |
| <p><strong>Java Side</strong></p> |
| <p>For this example, we will use <a class="reference external" href="https://github.com/bytedeco/javacpp">JavaCPP</a> to call our C++ function from Java, |
| without writing JNI bindings ourselves.</p> |
| <div class="highlight-xml notranslate"><div class="highlight"><pre><span></span><span class="cp"><?xml version="1.0" encoding="UTF-8"?></span> |
| <span class="nt"><project</span><span class="w"> </span><span class="na">xmlns=</span><span class="s">"http://maven.apache.org/POM/4.0.0"</span> |
| <span class="w"> </span><span class="na">xmlns:xsi=</span><span class="s">"http://www.w3.org/2001/XMLSchema-instance"</span> |
| <span class="w"> </span><span class="na">xsi:schemaLocation=</span><span class="s">"http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"</span><span class="nt">></span> |
| <span class="w"> </span><span class="nt"><modelVersion></span>4.0.0<span class="nt"></modelVersion></span> |
| |
| <span class="w"> </span><span class="nt"><groupId></span>org.example<span class="nt"></groupId></span> |
| <span class="w"> </span><span class="nt"><artifactId></span>java-cdata-example<span class="nt"></artifactId></span> |
| <span class="w"> </span><span class="nt"><version></span>1.0-SNAPSHOT<span class="nt"></version></span> |
| |
| <span class="w"> </span><span class="nt"><properties></span> |
| <span class="w"> </span><span class="nt"><maven.compiler.source></span>8<span class="nt"></maven.compiler.source></span> |
| <span class="w"> </span><span class="nt"><maven.compiler.target></span>8<span class="nt"></maven.compiler.target></span> |
| <span class="w"> </span><span class="nt"><arrow.version></span>9.0.0<span class="nt"></arrow.version></span> |
| <span class="w"> </span><span class="nt"></properties></span> |
| <span class="w"> </span><span class="nt"><dependencies></span> |
| <span class="w"> </span><span class="nt"><dependency></span> |
| <span class="w"> </span><span class="nt"><groupId></span>org.bytedeco<span class="nt"></groupId></span> |
| <span class="w"> </span><span class="nt"><artifactId></span>javacpp<span class="nt"></artifactId></span> |
| <span class="w"> </span><span class="nt"><version></span>1.5.7<span class="nt"></version></span> |
| <span class="w"> </span><span class="nt"></dependency></span> |
| <span class="w"> </span><span class="nt"><dependency></span> |
| <span class="w"> </span><span class="nt"><groupId></span>org.apache.arrow<span class="nt"></groupId></span> |
| <span class="w"> </span><span class="nt"><artifactId></span>arrow-c-data<span class="nt"></artifactId></span> |
| <span class="w"> </span><span class="nt"><version></span>${arrow.version}<span class="nt"></version></span> |
| <span class="w"> </span><span class="nt"></dependency></span> |
| <span class="w"> </span><span class="nt"><dependency></span> |
| <span class="w"> </span><span class="nt"><groupId></span>org.apache.arrow<span class="nt"></groupId></span> |
| <span class="w"> </span><span class="nt"><artifactId></span>arrow-vector<span class="nt"></artifactId></span> |
| <span class="w"> </span><span class="nt"><version></span>${arrow.version}<span class="nt"></version></span> |
| <span class="w"> </span><span class="nt"></dependency></span> |
| <span class="w"> </span><span class="nt"><dependency></span> |
| <span class="w"> </span><span class="nt"><groupId></span>org.apache.arrow<span class="nt"></groupId></span> |
| <span class="w"> </span><span class="nt"><artifactId></span>arrow-memory-core<span class="nt"></artifactId></span> |
| <span class="w"> </span><span class="nt"><version></span>${arrow.version}<span class="nt"></version></span> |
| <span class="w"> </span><span class="nt"></dependency></span> |
| <span class="w"> </span><span class="nt"><dependency></span> |
| <span class="w"> </span><span class="nt"><groupId></span>org.apache.arrow<span class="nt"></groupId></span> |
| <span class="w"> </span><span class="nt"><artifactId></span>arrow-memory-netty<span class="nt"></artifactId></span> |
| <span class="w"> </span><span class="nt"><version></span>${arrow.version}<span class="nt"></version></span> |
| <span class="w"> </span><span class="nt"></dependency></span> |
| <span class="w"> </span><span class="nt"><dependency></span> |
| <span class="w"> </span><span class="nt"><groupId></span>org.apache.arrow<span class="nt"></groupId></span> |
| <span class="w"> </span><span class="nt"><artifactId></span>arrow-format<span class="nt"></artifactId></span> |
| <span class="w"> </span><span class="nt"><version></span>${arrow.version}<span class="nt"></version></span> |
| <span class="w"> </span><span class="nt"></dependency></span> |
| <span class="w"> </span><span class="nt"></dependencies></span> |
| <span class="nt"></project></span> |
| </pre></div> |
| </div> |
| <div class="highlight-java notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">org.bytedeco.javacpp.annotation.Platform</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.bytedeco.javacpp.annotation.Properties</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.bytedeco.javacpp.tools.InfoMap</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.bytedeco.javacpp.tools.InfoMapper</span><span class="p">;</span> |
| |
| <span class="nd">@Properties</span><span class="p">(</span> |
| <span class="w"> </span><span class="n">target</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"CDataJavaToCppExample"</span><span class="p">,</span> |
| <span class="w"> </span><span class="n">value</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nd">@Platform</span><span class="p">(</span> |
| <span class="w"> </span><span class="n">include</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="s">"CDataCppBridge.h"</span> |
| <span class="w"> </span><span class="p">},</span> |
| <span class="w"> </span><span class="n">compiler</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">{</span><span class="s">"cpp17"</span><span class="p">},</span> |
| <span class="w"> </span><span class="n">linkpath</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">{</span><span class="s">"/arrow/cpp/build/debug/"</span><span class="p">},</span> |
| <span class="w"> </span><span class="n">link</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">{</span><span class="s">"arrow"</span><span class="p">}</span> |
| <span class="w"> </span><span class="p">)</span> |
| <span class="p">)</span> |
| <span class="kd">public</span><span class="w"> </span><span class="kd">class</span> <span class="nc">CDataJavaConfig</span><span class="w"> </span><span class="kd">implements</span><span class="w"> </span><span class="n">InfoMapper</span><span class="w"> </span><span class="p">{</span> |
| |
| <span class="w"> </span><span class="nd">@Override</span> |
| <span class="w"> </span><span class="kd">public</span><span class="w"> </span><span class="kt">void</span><span class="w"> </span><span class="nf">map</span><span class="p">(</span><span class="n">InfoMap</span><span class="w"> </span><span class="n">infoMap</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="p">}</span> |
| </pre></div> |
| </div> |
| <div class="highlight-shell notranslate"><div class="highlight"><pre><span></span><span class="c1"># Compile our Java code</span> |
| $<span class="w"> </span>javac<span class="w"> </span>-cp<span class="w"> </span>javacpp-1.5.7.jar<span class="w"> </span>CDataJavaConfig.java |
| |
| <span class="c1"># Generate CDataInterfaceLibrary</span> |
| $<span class="w"> </span>java<span class="w"> </span>-jar<span class="w"> </span>javacpp-1.5.7.jar<span class="w"> </span>CDataJavaConfig.java |
| |
| <span class="c1"># Generate libjniCDataInterfaceLibrary.dylib</span> |
| $<span class="w"> </span>java<span class="w"> </span>-jar<span class="w"> </span>javacpp-1.5.7.jar<span class="w"> </span>CDataJavaToCppExample.java |
| |
| <span class="c1"># Validate libjniCDataInterfaceLibrary.dylib created</span> |
| $<span class="w"> </span>otool<span class="w"> </span>-L<span class="w"> </span>macosx-x86_64/libjniCDataJavaToCppExample.dylib |
| macosx-x86_64/libjniCDataJavaToCppExample.dylib: |
| <span class="w"> </span>libjniCDataJavaToCppExample.dylib<span class="w"> </span><span class="o">(</span>compatibility<span class="w"> </span>version<span class="w"> </span><span class="m">0</span>.0.0,<span class="w"> </span>current<span class="w"> </span>version<span class="w"> </span><span class="m">0</span>.0.0<span class="o">)</span> |
| <span class="w"> </span>@rpath/libarrow.800.dylib<span class="w"> </span><span class="o">(</span>compatibility<span class="w"> </span>version<span class="w"> </span><span class="m">800</span>.0.0,<span class="w"> </span>current<span class="w"> </span>version<span class="w"> </span><span class="m">800</span>.0.0<span class="o">)</span> |
| <span class="w"> </span>/usr/lib/libc++.1.dylib<span class="w"> </span><span class="o">(</span>compatibility<span class="w"> </span>version<span class="w"> </span><span class="m">1</span>.0.0,<span class="w"> </span>current<span class="w"> </span>version<span class="w"> </span><span class="m">1200</span>.3.0<span class="o">)</span> |
| <span class="w"> </span>/usr/lib/libSystem.B.dylib<span class="w"> </span><span class="o">(</span>compatibility<span class="w"> </span>version<span class="w"> </span><span class="m">1</span>.0.0,<span class="w"> </span>current<span class="w"> </span>version<span class="w"> </span><span class="m">1311</span>.0.0<span class="o">)</span> |
| </pre></div> |
| </div> |
| <p><strong>Java Test</strong></p> |
| <p>Let’s create a Java class to test our bridge:</p> |
| <div class="highlight-java notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.c.ArrowArray</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.c.ArrowSchema</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.c.Data</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.memory.BufferAllocator</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.memory.RootAllocator</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.BigIntVector</span><span class="p">;</span> |
| |
| <span class="kd">public</span><span class="w"> </span><span class="kd">class</span> <span class="nc">TestCDataInterface</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="kd">public</span><span class="w"> </span><span class="kd">static</span><span class="w"> </span><span class="kt">void</span><span class="w"> </span><span class="nf">main</span><span class="p">(</span><span class="n">String</span><span class="o">[]</span><span class="w"> </span><span class="n">args</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="k">try</span><span class="p">(</span> |
| <span class="w"> </span><span class="n">BufferAllocator</span><span class="w"> </span><span class="n">allocator</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">RootAllocator</span><span class="p">();</span> |
| <span class="w"> </span><span class="n">ArrowSchema</span><span class="w"> </span><span class="n">arrowSchema</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ArrowSchema</span><span class="p">.</span><span class="na">allocateNew</span><span class="p">(</span><span class="n">allocator</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">ArrowArray</span><span class="w"> </span><span class="n">arrowArray</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ArrowArray</span><span class="p">.</span><span class="na">allocateNew</span><span class="p">(</span><span class="n">allocator</span><span class="p">)</span> |
| <span class="w"> </span><span class="p">){</span> |
| <span class="w"> </span><span class="n">CDataJavaToCppExample</span><span class="p">.</span><span class="na">FillInt64Array</span><span class="p">(</span> |
| <span class="w"> </span><span class="n">arrowSchema</span><span class="p">.</span><span class="na">memoryAddress</span><span class="p">(),</span><span class="w"> </span><span class="n">arrowArray</span><span class="p">.</span><span class="na">memoryAddress</span><span class="p">());</span> |
| <span class="w"> </span><span class="k">try</span><span class="p">(</span> |
| <span class="w"> </span><span class="n">BigIntVector</span><span class="w"> </span><span class="n">bigIntVector</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="n">BigIntVector</span><span class="p">)</span><span class="w"> </span><span class="n">Data</span><span class="p">.</span><span class="na">importVector</span><span class="p">(</span> |
| <span class="w"> </span><span class="n">allocator</span><span class="p">,</span><span class="w"> </span><span class="n">arrowArray</span><span class="p">,</span><span class="w"> </span><span class="n">arrowSchema</span><span class="p">,</span><span class="w"> </span><span class="kc">null</span><span class="p">)</span> |
| <span class="w"> </span><span class="p">){</span> |
| <span class="w"> </span><span class="n">System</span><span class="p">.</span><span class="na">out</span><span class="p">.</span><span class="na">println</span><span class="p">(</span><span class="s">"C++-allocated array: "</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">bigIntVector</span><span class="p">);</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="p">}</span> |
| </pre></div> |
| </div> |
| <div class="highlight-shell notranslate"><div class="highlight"><pre><span></span>C++-allocated<span class="w"> </span>array:<span class="w"> </span><span class="o">[</span><span class="m">1</span>,<span class="w"> </span><span class="m">2</span>,<span class="w"> </span><span class="m">3</span>,<span class="w"> </span>null,<span class="w"> </span><span class="m">5</span>,<span class="w"> </span><span class="m">6</span>,<span class="w"> </span><span class="m">7</span>,<span class="w"> </span><span class="m">8</span>,<span class="w"> </span><span class="m">9</span>,<span class="w"> </span><span class="m">10</span><span class="o">]</span> |
| </pre></div> |
| </div> |
| </section> |
| <section id="share-an-int32-array-from-java-to-c"> |
| <h3>Share an Int32 array from Java to C++<a class="headerlink" href="#share-an-int32-array-from-java-to-c" title="Link to this heading">¶</a></h3> |
| <p><strong>Java Side</strong></p> |
| <p>For this example, we will build a JAR with all dependencies bundled.</p> |
| <div class="highlight-xml notranslate"><div class="highlight"><pre><span></span><span class="cp"><?xml version="1.0" encoding="UTF-8"?></span> |
| <span class="nt"><project</span><span class="w"> </span><span class="na">xmlns=</span><span class="s">"http://maven.apache.org/POM/4.0.0"</span> |
| <span class="w"> </span><span class="na">xmlns:xsi=</span><span class="s">"http://www.w3.org/2001/XMLSchema-instance"</span> |
| <span class="w"> </span><span class="na">xsi:schemaLocation=</span><span class="s">"http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"</span><span class="nt">></span> |
| <span class="w"> </span><span class="nt"><modelVersion></span>4.0.0<span class="nt"></modelVersion></span> |
| <span class="w"> </span><span class="nt"><groupId></span>org.example<span class="nt"></groupId></span> |
| <span class="w"> </span><span class="nt"><artifactId></span>cpptojava<span class="nt"></artifactId></span> |
| <span class="w"> </span><span class="nt"><version></span>1.0-SNAPSHOT<span class="nt"></version></span> |
| <span class="w"> </span><span class="nt"><properties></span> |
| <span class="w"> </span><span class="nt"><maven.compiler.source></span>8<span class="nt"></maven.compiler.source></span> |
| <span class="w"> </span><span class="nt"><maven.compiler.target></span>8<span class="nt"></maven.compiler.target></span> |
| <span class="w"> </span><span class="nt"><arrow.version></span>9.0.0<span class="nt"></arrow.version></span> |
| <span class="w"> </span><span class="nt"></properties></span> |
| <span class="w"> </span><span class="nt"><dependencies></span> |
| <span class="w"> </span><span class="nt"><dependency></span> |
| <span class="w"> </span><span class="nt"><groupId></span>org.apache.arrow<span class="nt"></groupId></span> |
| <span class="w"> </span><span class="nt"><artifactId></span>arrow-c-data<span class="nt"></artifactId></span> |
| <span class="w"> </span><span class="nt"><version></span>${arrow.version}<span class="nt"></version></span> |
| <span class="w"> </span><span class="nt"></dependency></span> |
| <span class="w"> </span><span class="nt"><dependency></span> |
| <span class="w"> </span><span class="nt"><groupId></span>org.apache.arrow<span class="nt"></groupId></span> |
| <span class="w"> </span><span class="nt"><artifactId></span>arrow-memory-netty<span class="nt"></artifactId></span> |
| <span class="w"> </span><span class="nt"><version></span>${arrow.version}<span class="nt"></version></span> |
| <span class="w"> </span><span class="nt"></dependency></span> |
| <span class="w"> </span><span class="nt"></dependencies></span> |
| <span class="w"> </span><span class="nt"><build></span> |
| <span class="w"> </span><span class="nt"><plugins></span> |
| <span class="w"> </span><span class="nt"><plugin></span> |
| <span class="w"> </span><span class="nt"><groupId></span>org.apache.maven.plugins<span class="nt"></groupId></span> |
| <span class="w"> </span><span class="nt"><artifactId></span>maven-assembly-plugin<span class="nt"></artifactId></span> |
| <span class="w"> </span><span class="nt"><executions></span> |
| <span class="w"> </span><span class="nt"><execution></span> |
| <span class="w"> </span><span class="nt"><phase></span>package<span class="nt"></phase></span> |
| <span class="w"> </span><span class="nt"><goals></span> |
| <span class="w"> </span><span class="nt"><goal></span>single<span class="nt"></goal></span> |
| <span class="w"> </span><span class="nt"></goals></span> |
| <span class="w"> </span><span class="nt"><configuration></span> |
| <span class="w"> </span><span class="nt"><descriptorRefs></span> |
| <span class="w"> </span><span class="nt"><descriptorRef></span>jar-with-dependencies<span class="nt"></descriptorRef></span> |
| <span class="w"> </span><span class="nt"></descriptorRefs></span> |
| <span class="w"> </span><span class="nt"></configuration></span> |
| <span class="w"> </span><span class="nt"></execution></span> |
| <span class="w"> </span><span class="nt"></executions></span> |
| <span class="w"> </span><span class="nt"></plugin></span> |
| <span class="w"> </span><span class="nt"></plugins></span> |
| <span class="w"> </span><span class="nt"></build></span> |
| <span class="nt"></project></span> |
| </pre></div> |
| </div> |
| <div class="highlight-java notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.c.ArrowArray</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.c.ArrowSchema</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.c.Data</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.memory.BufferAllocator</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.memory.RootAllocator</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.FieldVector</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.IntVector</span><span class="p">;</span> |
| <span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.VectorSchemaRoot</span><span class="p">;</span> |
| |
| <span class="kn">import</span><span class="w"> </span><span class="nn">java.util.Arrays</span><span class="p">;</span> |
| |
| <span class="kd">public</span><span class="w"> </span><span class="kd">class</span> <span class="nc">ToBeCalledByCpp</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="kd">final</span><span class="w"> </span><span class="kd">static</span><span class="w"> </span><span class="n">BufferAllocator</span><span class="w"> </span><span class="n">allocator</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">RootAllocator</span><span class="p">();</span> |
| |
| <span class="w"> </span><span class="cm">/**</span> |
| <span class="cm"> * Create a {@link FieldVector} and export it via the C Data Interface</span> |
| <span class="cm"> * @param schemaAddress Schema memory address to wrap</span> |
| <span class="cm"> * @param arrayAddress Array memory address to wrap</span> |
| <span class="cm"> */</span> |
| <span class="w"> </span><span class="kd">public</span><span class="w"> </span><span class="kd">static</span><span class="w"> </span><span class="kt">void</span><span class="w"> </span><span class="nf">fillVector</span><span class="p">(</span><span class="kt">long</span><span class="w"> </span><span class="n">schemaAddress</span><span class="p">,</span><span class="w"> </span><span class="kt">long</span><span class="w"> </span><span class="n">arrayAddress</span><span class="p">){</span> |
| <span class="w"> </span><span class="k">try</span><span class="w"> </span><span class="p">(</span><span class="n">ArrowArray</span><span class="w"> </span><span class="n">arrow_array</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ArrowArray</span><span class="p">.</span><span class="na">wrap</span><span class="p">(</span><span class="n">arrayAddress</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">ArrowSchema</span><span class="w"> </span><span class="n">arrow_schema</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ArrowSchema</span><span class="p">.</span><span class="na">wrap</span><span class="p">(</span><span class="n">schemaAddress</span><span class="p">)</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">Data</span><span class="p">.</span><span class="na">exportVector</span><span class="p">(</span><span class="n">allocator</span><span class="p">,</span><span class="w"> </span><span class="n">populateFieldVectorToExport</span><span class="p">(),</span><span class="w"> </span><span class="kc">null</span><span class="p">,</span><span class="w"> </span><span class="n">arrow_array</span><span class="p">,</span><span class="w"> </span><span class="n">arrow_schema</span><span class="p">);</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="w"> </span><span class="p">}</span> |
| |
| <span class="w"> </span><span class="cm">/**</span> |
| <span class="cm"> * Create a {@link VectorSchemaRoot} and export it via the C Data Interface</span> |
| <span class="cm"> * @param schemaAddress Schema memory address to wrap</span> |
| <span class="cm"> * @param arrayAddress Array memory address to wrap</span> |
| <span class="cm"> */</span> |
| <span class="w"> </span><span class="kd">public</span><span class="w"> </span><span class="kd">static</span><span class="w"> </span><span class="kt">void</span><span class="w"> </span><span class="nf">fillVectorSchemaRoot</span><span class="p">(</span><span class="kt">long</span><span class="w"> </span><span class="n">schemaAddress</span><span class="p">,</span><span class="w"> </span><span class="kt">long</span><span class="w"> </span><span class="n">arrayAddress</span><span class="p">){</span> |
| <span class="w"> </span><span class="k">try</span><span class="w"> </span><span class="p">(</span><span class="n">ArrowArray</span><span class="w"> </span><span class="n">arrow_array</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ArrowArray</span><span class="p">.</span><span class="na">wrap</span><span class="p">(</span><span class="n">arrayAddress</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">ArrowSchema</span><span class="w"> </span><span class="n">arrow_schema</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ArrowSchema</span><span class="p">.</span><span class="na">wrap</span><span class="p">(</span><span class="n">schemaAddress</span><span class="p">)</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">Data</span><span class="p">.</span><span class="na">exportVectorSchemaRoot</span><span class="p">(</span><span class="n">allocator</span><span class="p">,</span><span class="w"> </span><span class="n">populateVectorSchemaRootToExport</span><span class="p">(),</span><span class="w"> </span><span class="kc">null</span><span class="p">,</span><span class="w"> </span><span class="n">arrow_array</span><span class="p">,</span><span class="w"> </span><span class="n">arrow_schema</span><span class="p">);</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="w"> </span><span class="p">}</span> |
| |
| <span class="w"> </span><span class="kd">private</span><span class="w"> </span><span class="kd">static</span><span class="w"> </span><span class="n">FieldVector</span><span class="w"> </span><span class="nf">populateFieldVectorToExport</span><span class="p">(){</span> |
| <span class="w"> </span><span class="n">IntVector</span><span class="w"> </span><span class="n">intVector</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">IntVector</span><span class="p">(</span><span class="s">"int-to-export"</span><span class="p">,</span><span class="w"> </span><span class="n">allocator</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">intVector</span><span class="p">.</span><span class="na">allocateNew</span><span class="p">(</span><span class="mi">3</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">intVector</span><span class="p">.</span><span class="na">setSafe</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">intVector</span><span class="p">.</span><span class="na">setSafe</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">intVector</span><span class="p">.</span><span class="na">setSafe</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">intVector</span><span class="p">.</span><span class="na">setValueCount</span><span class="p">(</span><span class="mi">3</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">System</span><span class="p">.</span><span class="na">out</span><span class="p">.</span><span class="na">println</span><span class="p">(</span><span class="s">"[Java] FieldVector: \n"</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">intVector</span><span class="p">);</span> |
| <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">intVector</span><span class="p">;</span> |
| <span class="w"> </span><span class="p">}</span> |
| |
| <span class="w"> </span><span class="kd">private</span><span class="w"> </span><span class="kd">static</span><span class="w"> </span><span class="n">VectorSchemaRoot</span><span class="w"> </span><span class="nf">populateVectorSchemaRootToExport</span><span class="p">(){</span> |
| <span class="w"> </span><span class="n">IntVector</span><span class="w"> </span><span class="n">intVector</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">IntVector</span><span class="p">(</span><span class="s">"age-to-export"</span><span class="p">,</span><span class="w"> </span><span class="n">allocator</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">intVector</span><span class="p">.</span><span class="na">setSafe</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">10</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">intVector</span><span class="p">.</span><span class="na">setSafe</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">20</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">intVector</span><span class="p">.</span><span class="na">setSafe</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">30</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">VectorSchemaRoot</span><span class="w"> </span><span class="n">root</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">VectorSchemaRoot</span><span class="p">(</span><span class="n">Arrays</span><span class="p">.</span><span class="na">asList</span><span class="p">(</span><span class="n">intVector</span><span class="p">));</span> |
| <span class="w"> </span><span class="n">root</span><span class="p">.</span><span class="na">setRowCount</span><span class="p">(</span><span class="mi">3</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">System</span><span class="p">.</span><span class="na">out</span><span class="p">.</span><span class="na">println</span><span class="p">(</span><span class="s">"[Java] VectorSchemaRoot: \n"</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">root</span><span class="p">.</span><span class="na">contentToTSVString</span><span class="p">());</span> |
| <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">root</span><span class="p">;</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="p">}</span> |
| </pre></div> |
| </div> |
| <p>Build the JAR and copy it to the C++ project.</p> |
| <div class="highlight-shell notranslate"><div class="highlight"><pre><span></span>$<span class="w"> </span>mvn<span class="w"> </span>clean<span class="w"> </span>install |
| $<span class="w"> </span>cp<span class="w"> </span>target/cpptojava-1.0-SNAPSHOT-jar-with-dependencies.jar<span class="w"> </span><c++<span class="w"> </span>project<span class="w"> </span>path>/cpptojava.jar |
| </pre></div> |
| </div> |
| <p><strong>C++ Side</strong></p> |
| <p>This application uses JNI to call Java code, but transfers data (zero-copy) via the C Data Interface instead.</p> |
| <div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><iostream></span> |
| <span class="cp">#include</span><span class="w"> </span><span class="cpf"><jni.h></span> |
| |
| <span class="cp">#include</span><span class="w"> </span><span class="cpf"><arrow/api.h></span> |
| <span class="cp">#include</span><span class="w"> </span><span class="cpf"><arrow/c/bridge.h></span> |
| |
| <span class="n">JNIEnv</span><span class="w"> </span><span class="o">*</span><span class="nf">CreateVM</span><span class="p">(</span><span class="n">JavaVM</span><span class="w"> </span><span class="o">**</span><span class="n">jvm</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">JNIEnv</span><span class="w"> </span><span class="o">*</span><span class="n">env</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">JavaVMInitArgs</span><span class="w"> </span><span class="n">vm_args</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">JavaVMOption</span><span class="w"> </span><span class="n">options</span><span class="p">[</span><span class="mi">2</span><span class="p">];</span> |
| <span class="w"> </span><span class="n">options</span><span class="p">[</span><span class="mi">0</span><span class="p">].</span><span class="n">optionString</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"-Djava.class.path=cpptojava.jar"</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">options</span><span class="p">[</span><span class="mi">1</span><span class="p">].</span><span class="n">optionString</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"-DXcheck:jni:pedantic"</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">vm_args</span><span class="p">.</span><span class="n">version</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">JNI_VERSION_10</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">vm_args</span><span class="p">.</span><span class="n">nOptions</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">vm_args</span><span class="p">.</span><span class="n">options</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">options</span><span class="p">;</span> |
| <span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">status</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">JNI_CreateJavaVM</span><span class="p">(</span><span class="n">jvm</span><span class="p">,</span><span class="w"> </span><span class="p">(</span><span class="kt">void</span><span class="w"> </span><span class="o">**</span><span class="p">)</span><span class="w"> </span><span class="o">&</span><span class="n">env</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">vm_args</span><span class="p">);</span> |
| <span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">status</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="mi">0</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">cerr</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"</span><span class="se">\n</span><span class="s"><<<<< Unable to Launch JVM >>>>></span><span class="se">\n</span><span class="s">"</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">endl</span><span class="p">;</span> |
| <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="k">nullptr</span><span class="p">;</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">env</span><span class="p">;</span> |
| <span class="p">}</span> |
| |
| <span class="kt">int</span><span class="w"> </span><span class="nf">main</span><span class="p">()</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">JNIEnv</span><span class="w"> </span><span class="o">*</span><span class="n">env</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">JavaVM</span><span class="w"> </span><span class="o">*</span><span class="n">jvm</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">env</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">CreateVM</span><span class="p">(</span><span class="o">&</span><span class="n">jvm</span><span class="p">);</span> |
| <span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">env</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="k">nullptr</span><span class="p">)</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">EXIT_FAILURE</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">jclass</span><span class="w"> </span><span class="n">javaClassToBeCalledByCpp</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">env</span><span class="o">-></span><span class="n">FindClass</span><span class="p">(</span><span class="s">"ToBeCalledByCpp"</span><span class="p">);</span> |
| <span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">javaClassToBeCalledByCpp</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="k">nullptr</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">jmethodID</span><span class="w"> </span><span class="n">fillVector</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">env</span><span class="o">-></span><span class="n">GetStaticMethodID</span><span class="p">(</span><span class="n">javaClassToBeCalledByCpp</span><span class="p">,</span> |
| <span class="w"> </span><span class="s">"fillVector"</span><span class="p">,</span> |
| <span class="w"> </span><span class="s">"(JJ)V"</span><span class="p">);</span> |
| <span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">fillVector</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="k">nullptr</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">ArrowSchema</span><span class="w"> </span><span class="n">arrowSchema</span><span class="p">;</span> |
| <span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">ArrowArray</span><span class="w"> </span><span class="n">arrowArray</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">cout</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"</span><span class="se">\n</span><span class="s"><<<<< C++ to Java for Arrays >>>>></span><span class="se">\n</span><span class="s">"</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">endl</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">env</span><span class="o">-></span><span class="n">CallStaticVoidMethod</span><span class="p">(</span><span class="n">javaClassToBeCalledByCpp</span><span class="p">,</span><span class="w"> </span><span class="n">fillVector</span><span class="p">,</span> |
| <span class="w"> </span><span class="k">static_cast</span><span class="o"><</span><span class="n">jlong</span><span class="o">></span><span class="p">(</span><span class="k">reinterpret_cast</span><span class="o"><</span><span class="kt">uintptr_t</span><span class="o">></span><span class="p">(</span><span class="o">&</span><span class="n">arrowSchema</span><span class="p">)),</span> |
| <span class="w"> </span><span class="k">static_cast</span><span class="o"><</span><span class="n">jlong</span><span class="o">></span><span class="p">(</span><span class="k">reinterpret_cast</span><span class="o"><</span><span class="kt">uintptr_t</span><span class="o">></span><span class="p">(</span><span class="o">&</span><span class="n">arrowArray</span><span class="p">)));</span> |
| <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">resultImportArray</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">ImportArray</span><span class="p">(</span><span class="o">&</span><span class="n">arrowArray</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">arrowSchema</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">Array</span><span class="o">></span><span class="w"> </span><span class="n">array</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">resultImportArray</span><span class="p">.</span><span class="n">ValueOrDie</span><span class="p">();</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">cout</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"[C++] Array: "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">array</span><span class="o">-></span><span class="n">ToString</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">endl</span><span class="p">;</span> |
| <span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">cerr</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"Could not find fillVector method</span><span class="se">\n</span><span class="s">"</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">endl</span><span class="p">;</span> |
| <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">EXIT_FAILURE</span><span class="p">;</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="w"> </span><span class="n">jmethodID</span><span class="w"> </span><span class="n">fillVectorSchemaRoot</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">env</span><span class="o">-></span><span class="n">GetStaticMethodID</span><span class="p">(</span><span class="n">javaClassToBeCalledByCpp</span><span class="p">,</span> |
| <span class="w"> </span><span class="s">"fillVectorSchemaRoot"</span><span class="p">,</span> |
| <span class="w"> </span><span class="s">"(JJ)V"</span><span class="p">);</span> |
| <span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">fillVectorSchemaRoot</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="k">nullptr</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">ArrowSchema</span><span class="w"> </span><span class="n">arrowSchema</span><span class="p">;</span> |
| <span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">ArrowArray</span><span class="w"> </span><span class="n">arrowArray</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">cout</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"</span><span class="se">\n</span><span class="s"><<<<< C++ to Java for RecordBatch >>>>></span><span class="se">\n</span><span class="s">"</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">endl</span><span class="p">;</span> |
| <span class="w"> </span><span class="n">env</span><span class="o">-></span><span class="n">CallStaticVoidMethod</span><span class="p">(</span><span class="n">javaClassToBeCalledByCpp</span><span class="p">,</span><span class="w"> </span><span class="n">fillVectorSchemaRoot</span><span class="p">,</span> |
| <span class="w"> </span><span class="k">static_cast</span><span class="o"><</span><span class="n">jlong</span><span class="o">></span><span class="p">(</span><span class="k">reinterpret_cast</span><span class="o"><</span><span class="kt">uintptr_t</span><span class="o">></span><span class="p">(</span><span class="o">&</span><span class="n">arrowSchema</span><span class="p">)),</span> |
| <span class="w"> </span><span class="k">static_cast</span><span class="o"><</span><span class="n">jlong</span><span class="o">></span><span class="p">(</span><span class="k">reinterpret_cast</span><span class="o"><</span><span class="kt">uintptr_t</span><span class="o">></span><span class="p">(</span><span class="o">&</span><span class="n">arrowArray</span><span class="p">)));</span> |
| <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">resultImportVectorSchemaRoot</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">arrow</span><span class="o">::</span><span class="n">ImportRecordBatch</span><span class="p">(</span><span class="o">&</span><span class="n">arrowArray</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">arrowSchema</span><span class="p">);</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">shared_ptr</span><span class="o"><</span><span class="n">arrow</span><span class="o">::</span><span class="n">RecordBatch</span><span class="o">></span><span class="w"> </span><span class="n">recordBatch</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">resultImportVectorSchemaRoot</span><span class="p">.</span><span class="n">ValueOrDie</span><span class="p">();</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">cout</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"[C++] RecordBatch: "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">recordBatch</span><span class="o">-></span><span class="n">ToString</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">endl</span><span class="p">;</span> |
| <span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">cerr</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"Could not find fillVectorSchemaRoot method</span><span class="se">\n</span><span class="s">"</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">endl</span><span class="p">;</span> |
| <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">EXIT_FAILURE</span><span class="p">;</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">cout</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"Could not find ToBeCalledByCpp class</span><span class="se">\n</span><span class="s">"</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">endl</span><span class="p">;</span> |
| <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">EXIT_FAILURE</span><span class="p">;</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="w"> </span><span class="n">jvm</span><span class="o">-></span><span class="n">DestroyJavaVM</span><span class="p">();</span> |
| <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">EXIT_SUCCESS</span><span class="p">;</span> |
| <span class="p">}</span> |
| </pre></div> |
| </div> |
| <p>CMakeLists.txt definition file:</p> |
| <div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nb">cmake_minimum_required</span><span class="p">(</span><span class="s">VERSION</span><span class="w"> </span><span class="s">3.19</span><span class="p">)</span> |
| <span class="nb">project</span><span class="p">(</span><span class="s">cdatacpptojava</span><span class="p">)</span> |
| <span class="nb">find_package</span><span class="p">(</span><span class="s">JNI</span><span class="w"> </span><span class="s">REQUIRED</span><span class="p">)</span> |
| <span class="nb">find_package</span><span class="p">(</span><span class="s">Arrow</span><span class="w"> </span><span class="s">REQUIRED</span><span class="p">)</span> |
| <span class="nb">message</span><span class="p">(</span><span class="s">STATUS</span><span class="w"> </span><span class="s2">"Arrow version: ${ARROW_VERSION}"</span><span class="p">)</span> |
| <span class="nb">include_directories</span><span class="p">(</span><span class="o">${</span><span class="nv">JNI_INCLUDE_DIRS</span><span class="o">}</span><span class="p">)</span> |
| <span class="nb">set</span><span class="p">(</span><span class="s">CMAKE_CXX_STANDARD</span><span class="w"> </span><span class="s">17</span><span class="p">)</span> |
| <span class="nb">add_executable</span><span class="p">(</span><span class="o">${</span><span class="nv">PROJECT_NAME</span><span class="o">}</span><span class="w"> </span><span class="s">main.cpp</span><span class="p">)</span> |
| <span class="nb">target_link_libraries</span><span class="p">(</span><span class="s">cdatacpptojava</span><span class="w"> </span><span class="s">PRIVATE</span><span class="w"> </span><span class="s">Arrow::arrow_shared</span><span class="p">)</span> |
| <span class="nb">target_link_libraries</span><span class="p">(</span><span class="s">cdatacpptojava</span><span class="w"> </span><span class="s">PRIVATE</span><span class="w"> </span><span class="o">${</span><span class="nv">JNI_LIBRARIES</span><span class="o">}</span><span class="p">)</span> |
| </pre></div> |
| </div> |
| <p><strong>Result</strong></p> |
| <div class="highlight-text notranslate"><div class="highlight"><pre><span></span><<<<< C++ to Java for Arrays >>>>> |
| [Java] FieldVector: |
| [1, 2, 3] |
| [C++] Array: [ |
| 1, |
| 2, |
| 3 |
| ] |
| |
| <<<<< C++ to Java for RecordBatch >>>>> |
| [Java] VectorSchemaRoot: |
| age-to-export |
| 10 |
| 20 |
| 30 |
| |
| [C++] RecordBatch: age-to-export: [ |
| 10, |
| 20, |
| 30 |
| ] |
| </pre></div> |
| </div> |
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