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</pre><pre class="rust"><code><span class="doccomment">//! table_cache implements a cache providing access to the immutable SSTables on disk. It&#39;s a
//! read-through cache, meaning that non-present tables are read from disk and cached before being
//! returned.
</span><span class="kw">use </span><span class="kw">crate</span>::cache::{<span class="self">self</span>, Cache};
<span class="kw">use </span><span class="kw">crate</span>::error::{err, <span class="prelude-ty">Result</span>, StatusCode};
<span class="kw">use </span><span class="kw">crate</span>::key_types::InternalKey;
<span class="kw">use </span><span class="kw">crate</span>::options::Options;
<span class="kw">use </span><span class="kw">crate</span>::table_reader::Table;
<span class="kw">use </span><span class="kw">crate</span>::types::FileNum;
<span class="kw">use </span>integer_encoding::FixedIntWriter;
<span class="kw">use </span>std::convert::AsRef;
<span class="kw">use </span>std::path::{Path, PathBuf};
<span class="kw">use </span>std::rc::Rc;
<span class="kw">pub fn </span>table_file_name&lt;P: AsRef&lt;Path&gt;&gt;(name: P, num: FileNum) -&gt; PathBuf {
<span class="macro">assert!</span>(num &gt; <span class="number">0</span>);
name.as_ref().join(<span class="macro">format!</span>(<span class="string">&quot;{:06}.ldb&quot;</span>, num))
}
<span class="kw">fn </span>filenum_to_key(num: FileNum) -&gt; cache::CacheKey {
<span class="kw">let </span><span class="kw-2">mut </span>buf = [<span class="number">0</span>; <span class="number">16</span>];
(<span class="kw-2">&amp;mut </span>buf[..]).write_fixedint(num).unwrap();
buf
}
<span class="kw">pub struct </span>TableCache {
dbname: PathBuf,
cache: Cache&lt;Table&gt;,
opts: Options,
}
<span class="kw">impl </span>TableCache {
<span class="doccomment">/// Create a new TableCache for the database named `db`, caching up to `entries` tables.
///
/// opt.cmp should be the user-supplied comparator.
</span><span class="kw">pub fn </span>new&lt;P: AsRef&lt;Path&gt;&gt;(db: P, opt: Options, entries: usize) -&gt; TableCache {
TableCache {
dbname: db.as_ref().to_owned(),
cache: Cache::new(entries),
opts: opt,
}
}
<span class="kw">pub fn </span>get&lt;<span class="lifetime">&#39;a</span>&gt;(
<span class="kw-2">&amp;mut </span><span class="self">self</span>,
file_num: FileNum,
key: InternalKey&lt;<span class="lifetime">&#39;a</span>&gt;,
) -&gt; <span class="prelude-ty">Result</span>&lt;<span class="prelude-ty">Option</span>&lt;(Vec&lt;u8&gt;, Vec&lt;u8&gt;)&gt;&gt; {
<span class="kw">let </span>tbl = <span class="self">self</span>.get_table(file_num)<span class="question-mark">?</span>;
tbl.get(key)
}
<span class="doccomment">/// Return a table from cache, or open the backing file, then cache and return it.
</span><span class="kw">pub fn </span>get_table(<span class="kw-2">&amp;mut </span><span class="self">self</span>, file_num: FileNum) -&gt; <span class="prelude-ty">Result</span>&lt;Table&gt; {
<span class="kw">let </span>key = filenum_to_key(file_num);
<span class="kw">if let </span><span class="prelude-val">Some</span>(t) = <span class="self">self</span>.cache.get(<span class="kw-2">&amp;</span>key) {
<span class="kw">return </span><span class="prelude-val">Ok</span>(t.clone());
}
<span class="self">self</span>.open_table(file_num)
}
<span class="doccomment">/// Open a table on the file system and read it.
</span><span class="kw">fn </span>open_table(<span class="kw-2">&amp;mut </span><span class="self">self</span>, file_num: FileNum) -&gt; <span class="prelude-ty">Result</span>&lt;Table&gt; {
<span class="kw">let </span>name = table_file_name(<span class="kw-2">&amp;</span><span class="self">self</span>.dbname, file_num);
<span class="kw">let </span>path = Path::new(<span class="kw-2">&amp;</span>name);
<span class="kw">let </span>file_size = <span class="self">self</span>.opts.env.size_of(<span class="kw-2">&amp;</span>path)<span class="question-mark">?</span>;
<span class="kw">if </span>file_size == <span class="number">0 </span>{
<span class="kw">return </span>err(StatusCode::InvalidData, <span class="string">&quot;file is empty&quot;</span>);
}
<span class="kw">let </span>file = Rc::new(<span class="self">self</span>.opts.env.open_random_access_file(<span class="kw-2">&amp;</span>path)<span class="question-mark">?</span>);
<span class="comment">// No SSTable file name compatibility.
</span><span class="kw">let </span>table = Table::new(<span class="self">self</span>.opts.clone(), file, file_size)<span class="question-mark">?</span>;
<span class="self">self</span>.cache.insert(<span class="kw-2">&amp;</span>filenum_to_key(file_num), table.clone());
<span class="prelude-val">Ok</span>(table)
}
<span class="kw">pub fn </span>evict(<span class="kw-2">&amp;mut </span><span class="self">self</span>, file_num: FileNum) -&gt; <span class="prelude-ty">Result</span>&lt;()&gt; {
<span class="kw">if </span><span class="self">self</span>.cache.remove(<span class="kw-2">&amp;</span>filenum_to_key(file_num)).is_some() {
<span class="prelude-val">Ok</span>(())
} <span class="kw">else </span>{
err(StatusCode::NotFound, <span class="string">&quot;table not present in cache&quot;</span>)
}
}
}
<span class="attribute">#[cfg(feature = <span class="string">&quot;enclave_unit_test&quot;</span>)]
</span><span class="kw">pub mod </span>tests {
<span class="kw">use super</span>::<span class="kw-2">*</span>;
<span class="kw">use </span><span class="kw">crate</span>::cache;
<span class="kw">use </span><span class="kw">crate</span>::mem_env::MemEnv;
<span class="kw">use </span><span class="kw">crate</span>::options;
<span class="kw">use </span><span class="kw">crate</span>::table_builder::TableBuilder;
<span class="kw">use </span><span class="kw">crate</span>::test_util::LdbIteratorIter;
<span class="kw">use </span>teaclave_test_utils::<span class="kw-2">*</span>;
<span class="kw">pub fn </span>run_tests() -&gt; bool {
<span class="macro">run_tests!</span>(test_table_file_name, test_filenum_to_key, test_table_cache,)
}
<span class="kw">fn </span>test_table_file_name() {
<span class="macro">assert_eq!</span>(Path::new(<span class="string">&quot;abc/000122.ldb&quot;</span>), table_file_name(<span class="string">&quot;abc&quot;</span>, <span class="number">122</span>));
<span class="macro">assert_eq!</span>(
Path::new(<span class="string">&quot;abc/1234567.ldb&quot;</span>),
table_file_name(<span class="string">&quot;abc&quot;</span>, <span class="number">1234567</span>)
);
}
<span class="kw">fn </span>make_key(a: u8, b: u8, c: u8) -&gt; cache::CacheKey {
[a, b, c, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>]
}
<span class="kw">fn </span>test_filenum_to_key() {
<span class="macro">assert_eq!</span>(make_key(<span class="number">16</span>, <span class="number">0</span>, <span class="number">0</span>), filenum_to_key(<span class="number">0x10</span>));
<span class="macro">assert_eq!</span>(make_key(<span class="number">16</span>, <span class="number">1</span>, <span class="number">0</span>), filenum_to_key(<span class="number">0x0110</span>));
<span class="macro">assert_eq!</span>(make_key(<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>), filenum_to_key(<span class="number">0x030201</span>));
}
<span class="kw">fn </span>write_table_to(o: Options, p: <span class="kw-2">&amp;</span>Path) {
<span class="kw">let </span>w = o.env.open_writable_file(p).unwrap();
<span class="kw">let </span><span class="kw-2">mut </span>b = TableBuilder::new_raw(o, w);
<span class="kw">let </span>data = <span class="macro">vec!</span>[
(<span class="string">&quot;abc&quot;</span>, <span class="string">&quot;def&quot;</span>),
(<span class="string">&quot;abd&quot;</span>, <span class="string">&quot;dee&quot;</span>),
(<span class="string">&quot;bcd&quot;</span>, <span class="string">&quot;asa&quot;</span>),
(<span class="string">&quot;bsr&quot;</span>, <span class="string">&quot;a00&quot;</span>),
];
<span class="kw">for </span><span class="kw-2">&amp;</span>(k, v) <span class="kw">in </span>data.iter() {
b.add(k.as_bytes(), v.as_bytes()).unwrap();
}
b.finish().unwrap();
}
<span class="kw">fn </span>test_table_cache() {
<span class="comment">// Tests that a table can be written to a MemFS file, read back by the table cache and
// parsed/iterated by the table reader.
</span><span class="kw">let </span><span class="kw-2">mut </span>opt = options::for_test();
opt.env = Rc::new(Box::new(MemEnv::new()));
<span class="kw">let </span>dbname = Path::new(<span class="string">&quot;testdb1&quot;</span>);
<span class="kw">let </span>tablename = table_file_name(dbname, <span class="number">123</span>);
<span class="kw">let </span>tblpath = Path::new(<span class="kw-2">&amp;</span>tablename);
write_table_to(opt.clone(), tblpath);
<span class="macro">assert!</span>(opt.env.exists(tblpath).unwrap());
<span class="macro">assert!</span>(opt.env.size_of(tblpath).unwrap() &gt; <span class="number">20</span>);
<span class="kw">let </span><span class="kw-2">mut </span>cache = TableCache::new(dbname, opt.clone(), <span class="number">10</span>);
<span class="macro">assert!</span>(cache.cache.get(<span class="kw-2">&amp;</span>filenum_to_key(<span class="number">123</span>)).is_none());
<span class="macro">assert_eq!</span>(
LdbIteratorIter::wrap(<span class="kw-2">&amp;mut </span>cache.get_table(<span class="number">123</span>).unwrap().iter()).count(),
<span class="number">4
</span>);
<span class="comment">// Test cached table.
</span><span class="macro">assert_eq!</span>(
LdbIteratorIter::wrap(<span class="kw-2">&amp;mut </span>cache.get_table(<span class="number">123</span>).unwrap().iter()).count(),
<span class="number">4
</span>);
<span class="macro">assert!</span>(cache.cache.get(<span class="kw-2">&amp;</span>filenum_to_key(<span class="number">123</span>)).is_some());
<span class="macro">assert!</span>(cache.evict(<span class="number">123</span>).is_ok());
<span class="macro">assert!</span>(cache.evict(<span class="number">123</span>).is_err());
<span class="macro">assert!</span>(cache.cache.get(<span class="kw-2">&amp;</span>filenum_to_key(<span class="number">123</span>)).is_none());
}
}
</code></pre></div>
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