首先需要编译Pegasus，编译完成后运行以下命令可以打包生产Cpp客户端库：
./run.sh pack_client
运行成功后，会在本地文件夹下生产pegasus-client-{version}-{platform}-{buildType}的文件夹以及tar.gz文件。在文件夹里面有个sample/文件夹，进去后可以运行make编译示例程序。
Cpp客户端由于使用了rdsn框架，所以配置文件较为复杂，如下：
[apps..default] run = true count = 1 ;network.client.RPC_CHANNEL_TCP = dsn::tools::sim_network_provider, 65536 ;network.client.RPC_CHANNEL_UDP = dsn::tools::sim_network_provider, 65536 ;network.server.0.RPC_CHANNEL_TCP = dsn::tools::sim_network_provider, 65536 [apps.mimic] type = dsn.app.mimic arguments = pools = THREAD_POOL_DEFAULT run = true count = 1 [core] ;tool = simulator ;tool = fastrun tool = nativerun ;toollets = tracer ;toollets = tracer, profiler, fault_injector pause_on_start = false cli_local = false cli_remote = false start_nfs = false logging_start_level = LOG_LEVEL_DEBUG logging_factory_name = dsn::tools::simple_logger logging_flush_on_exit = true enable_default_app_mimic = true data_dir = ./data [tools.simple_logger] short_header = true fast_flush = true max_number_of_log_files_on_disk = 10 stderr_start_level = LOG_LEVEL_ERROR [tools.hpc_logger] per_thread_buffer_bytes = 8192 max_number_of_log_files_on_disk = 10 [tools.simulator] random_seed = 0 [network] ; how many network threads for network library(used by asio) io_service_worker_count = 4 ; specification for each thread pool [threadpool..default] worker_count = 4 [threadpool.THREAD_POOL_DEFAULT] name = default partitioned = false max_input_queue_length = 1024 worker_priority = THREAD_xPRIORITY_NORMAL worker_count = 4 [task..default] is_trace = false is_profile = false allow_inline = false fast_execution_in_network_thread = false rpc_call_header_format = NET_HDR_DSN rpc_call_channel = RPC_CHANNEL_TCP rpc_timeout_milliseconds = 5000 [pegasus.clusters] onebox = @LOCAL_IP@:34601,@LOCAL_IP@:34602,@LOCAL_IP@:34603 another_cluster = @SOME_IP@:34601,@SOME_IP@:34601,@SOME_IP@:34601
配置文件的具体解释，请移步 配置说明 。
客户端工厂类
namespace pegasus {
class pegasus_client_factory
{
public:
///
/// \brief initialize
/// initialize pegasus client lib. must call this function before anything else.
/// \param config_file
/// the configuration file of client lib
/// \return
/// true indicate the initailize is success.
///
static bool initialize(const char *config_file);
///
/// \brief get_client
/// get an instance for a given cluster and a given app name.
/// \param cluster_name
/// the pegasus cluster name.
/// a cluster can have multiple apps.
/// \param app_name
/// an app is a logical isolated k-v store.
/// a cluster can have multiple apps.
/// \return
/// the client instance. DO NOT delete this client even after usage.
static pegasus_client *get_client(const char *cluster_name, const char *app_name);
};
} //end namespace
客户端的初始化，实际上是对rdsn框架初始化
if (!pegasus::pegasus_client_factory::initialize("config.ini")) {
fprintf(stderr, "ERROR: init pegasus failed\n");
return -1;
}
/**succeed， continue**/
注：
获取客户端
pegasus::pegasus_client* pg_client = pegasus::pegasus_client_factory::get_client("cluster_name", "table_name");
if (pg_client == nullptr) {
fprintf(stderr, "ERROR: get pegasus client failed\n");
return -1;
}
/*** do what you want with pg_client ****/
注意： get_client返回值不能明确的调用delete，也不能用智能指针封装，框架在停止的时候自动释放（底层使用单例来保存）
Cpp客户端提供两种接口，异步API 和 同步API，同步API是基于异步API实现的，具体如下：
写单行数据
///
/// \brief set
/// store the k-v to the cluster.
/// key is composed of hashkey and sortkey.
/// \param hashkey
/// used to decide which partition to put this k-v
/// \param sortkey
/// all the k-v under hashkey will be sorted by sortkey.
/// \param value
/// the value we want to store.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \param ttl_seconds
/// time to live of this value, if expired, will return not found; 0 means no ttl
/// \return
/// int, the error indicates whether or not the operation is succeeded.
/// this error can be converted to a string using get_error_string()
///
virtual int set(const std::string &hashkey,
const std::string &sortkey,
const std::string &value,
int timeout_milliseconds = 5000,
int ttl_seconds = 0,
internal_info *info = NULL) = 0;
注：
struct internal_info
{
int32_t app_id;
int32_t partition_index;
int64_t decree;
std::string server;
internal_info() : app_id(-1), partition_index(-1), decree(-1) {}
}
///
/// \brief get_error_string
/// get error string
/// all the function above return an int value that indicates an error can be converted into a
/// string for human reading.
/// \param error_code
/// all the error code are defined in "error_def.h"
/// \return
///
virtual const char *get_error_string(int error_code) const = 0;
异步写单行数据
///
/// \brief asynchronous set
/// store the k-v to the cluster.
/// will not be blocked, return immediately.
/// key is composed of hashkey and sortkey.
/// \param hashkey
/// used to decide which partition to put this k-v
/// \param sortkey
/// all the k-v under hashkey will be stored by sortkey.
/// \param value
/// the value we want to store.
/// \param callback
/// the callback function will be invoked after operation finished or error occurred.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error.
/// \param ttl_seconds
/// time to live of this value, if expired, will return not found; 0 means no ttl.
/// \return
/// void.
///
virtual void async_set(const std::string &hashkey,
const std::string &sortkey,
const std::string &value,
async_set_callback_t &&callback = nullptr,
int timeout_milliseconds = 5000,
int ttl_seconds = 0) = 0;
写多条数据（同一hashkey下面）
///
/// \brief multi_set (guarantee atomicity)
/// store multiple k-v of the same hashkey to the cluster.
/// \param hashkey
/// used to decide which partition to put this k-v
/// \param kvs
/// all <sortkey,value> pairs to be set. should not be empty
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \param ttl_seconds
/// time to live of this value, if expired, will return not found; 0 means no ttl
/// \return
/// int, the error indicates whether or not the operation is succeeded.
/// this error can be converted to a string using get_error_string().
/// return PERR_INVALID_ARGUMENT if param kvs is empty.
///
virtual int multi_set(const std::string &hashkey,
const std::map<std::string, std::string> &kvs,
int timeout_milliseconds = 5000,
int ttl_seconds = 0,
internal_info *info = NULL) = 0;
异步写多条数据
///
/// \brief asynchronous multi_set (guarantee atomicity)
/// store multiple k-v of the same hashkey to the cluster.
/// will not be blocked, return immediately.
/// \param hashkey
/// used to decide which partition to put this k-v
/// \param kvs
/// all <sortkey,value> pairs to be set. should not be empty
/// \param callback
/// the callback function will be invoked after operation finished or error occurred.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \param ttl_seconds
/// time to live of this value, if expired, will return not found; 0 means no ttl
/// \return
/// void.
///
virtual void async_multi_set(const std::string &hashkey,
const std::map<std::string, std::string> &kvs,
async_multi_set_callback_t &&callback = nullptr,
int timeout_milliseconds = 5000,
int ttl_seconds = 0) = 0;
读取一条数据
///
/// \brief get
/// get value by key from the cluster.
/// \param hashkey
/// used to decide which partition to get this k-v
/// \param sortkey
/// all the k-v under hashkey will be sorted by sortkey.
/// \param value
/// the returned value will be put into it.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \return
/// int, the error indicates whether or not the operation is succeeded.
/// this error can be converted to a string using get_error_string().
/// returns PERR_NOT_FOUND if no value is found under the <hashkey,sortkey>.
///
virtual int get(const std::string &hashkey,
const std::string &sortkey,
std::string &value,
int timeout_milliseconds = 5000,
internal_info *info = NULL) = 0;
异步读取一条数据
///
/// \brief asynchronous get
/// get value by key from the cluster.
/// will not be blocked, return immediately.
/// \param hashkey
/// used to decide which partition to get this k-v
/// \param sortkey
/// all the k-v under hashkey will be sorted by sortkey.
/// \param callback
/// the callback function will be invoked after operation finished or error occurred.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \return
/// void.
///
virtual void async_get(const std::string &hashkey,
const std::string &sortkey,
async_get_callback_t &&callback = nullptr,
int timeout_milliseconds = 5000) = 0;
读取多条数据
///
/// \brief multi_get
/// get multiple value by key from the cluster.
/// \param hashkey
/// used to decide which partition to get this k-v
/// \param sortkeys
/// all the k-v under hashkey will be sorted by sortkey.
/// if empty, means fetch all sortkeys under the hashkey.
/// \param values
/// the returned <sortkey,value> pairs will be put into it.
/// if data is not found for some <hashkey,sortkey>, then it will not appear in the map.
/// \param max_fetch_count
/// max count of k-v pairs to be fetched. max_fetch_count <= 0 means no limit.
/// \param max_fetch_size
/// max size of k-v pairs to be fetched. max_fetch_size <= 0 means no limit.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \return
/// int, the error indicates whether or not the operation is succeeded.
/// this error can be converted to a string using get_error_string().
/// returns PERR_OK if fetch done, even no data is returned.
/// returns PERR_INCOMPLETE is only partial data is fetched.
///
virtual int multi_get(const std::string &hashkey,
const std::set<std::string> &sortkeys,
std::map<std::string, std::string> &values,
int max_fetch_count = 100,
int max_fetch_size = 1000000,
int timeout_milliseconds = 5000,
internal_info *info = NULL) = 0;
注：max_fetch_count 和 max_fetch_size 分别从kv-pair的条数 和 总的大小来限制multi_get的返回值
异步读取多条数据
///
/// \brief asynchronous multi_get
/// get multiple value by key from the cluster.
/// will not be blocked, return immediately.
/// \param hashkey
/// used to decide which partition to get this k-v
/// \param sortkeys
/// all the k-v under hashkey will be sorted by sortkey.
/// if empty, means fetch all sortkeys under the hashkey.
/// \param callback
/// the callback function will be invoked after operation finished or error occurred.
/// \param max_fetch_count
/// max count of k-v pairs to be fetched. max_fetch_count <= 0 means no limit.
/// \param max_fetch_size
/// max size of k-v pairs to be fetched. max_fetch_size <= 0 means no limit.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \return
/// void.
///
virtual void async_multi_get(const std::string &hashkey,
const std::set<std::string> &sortkeys,
async_multi_get_callback_t &&callback = nullptr,
int max_fetch_count = 100,
int max_fetch_size = 1000000,
int timeout_milliseconds = 5000) = 0;
获取hashkey下面的多个sortkey，不返回value
///
/// \brief multi_get_sortkeys
/// get multiple sort keys by hash key from the cluster.
/// only fetch sort keys, but not fetch values.
/// \param hashkey
/// used to decide which partition to get this k-v
/// \param sortkeys
/// the returned sort keys will be put into it.
/// \param max_fetch_count
/// max count of sort keys to be fetched. max_fetch_count <= 0 means no limit.
/// \param max_fetch_size
/// max size of sort keys to be fetched. max_fetch_size <= 0 means no limit.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \return
/// int, the error indicates whether or not the operation is succeeded.
/// this error can be converted to a string using get_error_string().
/// returns PERR_OK if fetch done, even no data is returned.
/// returns PERR_INCOMPLETE is only partial data is fetched.
///
virtual int multi_get_sortkeys(const std::string &hashkey,
std::set<std::string> &sortkeys,
int max_fetch_count = 100,
int max_fetch_size = 1000000,
int timeout_milliseconds = 5000,
internal_info *info = NULL) = 0;
注：max_fetch_count 和 max_fetch_size 分别限制返回的sortkey的个数与总大小（计算大小的时候，为每条sortkey都计算一次hashkey的大小）
异步获取hashkey下面的多个sortkey（不包含value）
///
/// \brief asynchronous multi_get_sortkeys
/// get multiple sort keys by hash key from the cluster.
/// only fetch sort keys, but not fetch values.
/// will not be blocked, return immediately.
/// \param hashkey
/// used to decide which partition to get this k-v
/// \param callback
/// the callback function will be invoked after operation finished or error occurred.
/// \param max_fetch_count
/// max count of sort keys to be fetched. max_fetch_count <= 0 means no limit.
/// \param max_fetch_size
/// max size of sort keys to be fetched. max_fetch_size <= 0 means no limit.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \return
/// void.
///
virtual void async_multi_get_sortkeys(const std::string &hashkey,
async_multi_get_sortkeys_callback_t &&callback = nullptr,
int max_fetch_count = 100,
int max_fetch_size = 1000000,
int timeout_milliseconds = 5000) = 0;
判断单条数据是否存在
///
/// \brief exist
/// check value exist by key from the cluster.
/// \param hashkey
/// used to decide which partition to get this k-v
/// \param sortkey
/// all the k-v under hashkey will be sorted by sortkey.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \return
/// int, the error indicates whether or not the operation is succeeded.
/// this error can be converted to a string using get_error_string().
/// returns PERR_OK if exist.
/// returns PERR_NOT_FOUND if not exist.
///
virtual int exist(const std::string &hashkey,
const std::string &sortkey,
int timeout_milliseconds = 5000,
internal_info *info = NULL) = 0;
统计hashkey下面的sortkey个数
///
/// \brief sortkey_count
/// get sortkey count by hashkey from the cluster.
/// \param hashkey
/// used to decide which partition to get this k-v
/// \param count
/// the returned sortkey count
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \return
/// int, the error indicates whether or not the operation is succeeded.
/// this error can be converted to a string using get_error_string().
///
virtual int sortkey_count(const std::string &hashkey,
int64_t &count,
int timeout_milliseconds = 5000,
internal_info *info = NULL) = 0;
删除单条数据
///
/// \brief del
/// del stored k-v by key from cluster
/// key is composed of hashkey and sortkey. must provide both to get the value.
/// \param hashkey
/// used to decide from which partition to del this k-v
/// \param sortkey
/// all the k-v under hashkey will be sorted by sortkey.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \return
/// int, the error indicates whether or not the operation is succeeded.
/// this error can be converted to a string using get_error_string()
///
virtual int del(const std::string &hashkey,
const std::string &sortkey,
int timeout_milliseconds = 5000,
internal_info *info = NULL) = 0;
异步删除单条数据
///
/// \brief asynchronous del
/// del stored k-v by key from cluster
/// key is composed of hashkey and sortkey. must provide both to get the value.
/// will not be blocked, return immediately.
/// \param hashkey
/// used to decide from which partition to del this k-v
/// \param sortkey
/// all the k-v under hashkey will be sorted by sortkey.
/// \param callback
/// the callback function will be invoked after operation finished or error occurred.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \return
/// void.
///
virtual void async_del(const std::string &hashkey,
const std::string &sortkey,
async_del_callback_t &&callback = nullptr,
int timeout_milliseconds = 5000) = 0;
删除多条数据
///
/// \brief multi_del
/// delete multiple value by key from the cluster.
/// \param hashkey
/// used to decide which partition to get this k-v
/// \param sortkeys
/// all the k-v under hashkey will be sorted by sortkey. should not be empty.
/// \param deleted_count
/// return count of deleted k-v pairs.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \return
/// int, the error indicates whether or not the operation is succeeded.
/// this error can be converted to a string using get_error_string().
///
virtual int multi_del(const std::string &hashkey,
const std::set<std::string> &sortkeys,
int64_t &deleted_count,
int timeout_milliseconds = 5000,
internal_info *info = NULL) = 0;
异步的删除多条数据
///
/// \brief asynchronous multi_del
/// delete multiple value by key from the cluster.
/// will not be blocked, return immediately.
/// \param hashkey
/// used to decide which partition to get this k-v
/// \param sortkeys
/// all the k-v under hashkey will be sorted by sortkey. should not be empty.
/// \param callback
/// the callback function will be invoked after operation finished or error occurred.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \return
/// void.
///
virtual void async_multi_del(const std::string &hashkey,
const std::set<std::string> &sortkeys,
async_multi_del_callback_t &&callback = nullptr,
int timeout_milliseconds = 5000) = 0;
获取单行数据的TTL时间。TTL表示Time To Live，表示该数据还能存活多久。如果超过存活时间，数据就读不到了
///
/// \brief ttl (time to live)
/// get ttl in seconds of this k-v.
/// key is composed of hashkey and sortkey. must provide both to get the value.
/// \param hashkey
/// used to decide which partition to get this k-v
/// \param sortkey
/// all the k-v under hashkey will be sorted by sortkey.
/// \param ttl_seconds
/// the returned ttl value in seconds.
/// \param timeout_milliseconds
/// if wait longer than this value, will return time out error
/// \return
/// int, the error indicates whether or not the operation is succeeded.
/// this error can be converted to a string using get_error_string()
///
virtual int ttl(const std::string &hashkey,
const std::string &sortkey,
int &ttl_seconds,
int timeout_milliseconds = 5000,
internal_info *info = NULL) = 0;
获取针对某个hashkey下的sortkey区间 [sortkeyA ~ sortkeyB)的一个scanner
///
/// \brief get hash scanner
/// get scanner for [start_sortkey, stop_sortkey) of hashkey
/// \param hashkey
/// cannot be empty
/// \param start_sortkey
/// sortkey to start with
/// \param stop_sortkey
/// sortkey to stop. ""(empty string) represents the max key
/// \param options
/// which used to indicate scan options, like which bound is inclusive
/// \param scanner
/// out param, used to get k-v
/// this pointer should be deleted when scan complete
/// \return
/// int, the error indicates whether or not the operation is succeeded.
/// this error can be converted to a string using get_error_string()
///
virtual int get_scanner(const std::string &hashkey,
const std::string &start_sortkey, // start from beginning if this set ""
const std::string &stop_sortkey, // to the last item if this set ""
const scan_options &options,
pegasus_scanner *&scanner) = 0;
异步获取针对某个hashkey下的sortkey区间 [sortkeyA ~ sortkeyB)的一个scanner
///
/// \brief async get hash scanner
/// get scanner for [start_sortkey, stop_sortkey) of hashkey
/// will not be blocked, return immediately.
/// \param hashkey
/// cannot be empty
/// \param start_sortkey
/// sortkey to start with
/// \param stop_sortkey
/// sortkey to stop. ""(empty string) represents the max key
/// \param options
/// which used to indicate scan options, like which bound is inclusive
/// \param callback
/// return status and scanner in callback, and the latter should be deleted when scan complete
///
virtual void
async_get_scanner(const std::string &hashkey,
const std::string &start_sortkey, // start from beginning if this set ""
const std::string &stop_sortkey, // to the last item if this set ""
const scan_options &options,
async_get_scanner_callback_t &&callback) = 0;
获取一个遍历所有数据的scanner
///
/// \brief get a bundle of scanners to iterate all k-v in table
/// scanners should be deleted when scan complete
/// \param max_split_count
/// the number of scanners returned will always <= max_split_count
/// \param options
/// which used to indicate scan options, like timeout_milliseconds
/// \param scanners
/// out param, used to get k-v
/// these pointers should be deleted
/// \return
/// int, the error indicates whether or not the operation is succeeded.
/// this error can be converted to a string using get_error_string()
///
virtual int get_unordered_scanners(int max_split_count,
const scan_options &options,
std::vector<pegasus_scanner *> &scanners) = 0;
异步获取一个遍历所有数据的scanner
///
/// \brief async get a bundle of scanners to iterate all k-v in table
/// scannners return by callback should be deleted when all scan complete
/// \param max_split_count
/// the number of scanners returned will always <= max_split_count
/// \param options
/// which used to indicate scan options, like timeout_milliseconds
/// \param callback; return status and scanner in this callback
///
virtual void
async_get_unordered_scanners(int max_split_count,
const scan_options &options,
async_get_unordered_scanners_callback_t &&callback) = 0;