mirror of https://github.com/facebook/rocksdb.git
109 lines
4.1 KiB
C++
109 lines
4.1 KiB
C++
/**
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* A (persistent) Redis API built using the rocksdb backend.
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* Implements Redis Lists as described on: http://redis.io/commands#list
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*
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* @throws All functions may throw a RedisListException
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*
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* @author Deon Nicholas (dnicholas@fb.com)
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* Copyright 2013 Facebook
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*/
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#ifndef ROCKSDB_LITE
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#pragma once
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#include <string>
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#include "rocksdb/db.h"
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#include "redis_list_iterator.h"
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#include "redis_list_exception.h"
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namespace rocksdb {
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/// The Redis functionality (see http://redis.io/commands#list)
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/// All functions may THROW a RedisListException
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class RedisLists {
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public: // Constructors / Destructors
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/// Construct a new RedisLists database, with name/path of db.
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/// Will clear the database on open iff destructive is true (default false).
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/// Otherwise, it will restore saved changes.
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/// May throw RedisListException
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RedisLists(const std::string& db_path,
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Options options, bool destructive = false);
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public: // Accessors
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/// The number of items in (list: key)
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int Length(const std::string& key);
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/// Search the list for the (index)'th item (0-based) in (list:key)
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/// A negative index indicates: "from end-of-list"
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/// If index is within range: return true, and return the value in *result.
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/// If (index < -length OR index>=length), then index is out of range:
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/// return false (and *result is left unchanged)
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/// May throw RedisListException
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bool Index(const std::string& key, int32_t index,
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std::string* result);
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/// Return (list: key)[first..last] (inclusive)
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/// May throw RedisListException
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std::vector<std::string> Range(const std::string& key,
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int32_t first, int32_t last);
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/// Prints the entire (list: key), for debugging.
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void Print(const std::string& key);
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public: // Insert/Update
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/// Insert value before/after pivot in (list: key). Return the length.
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/// May throw RedisListException
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int InsertBefore(const std::string& key, const std::string& pivot,
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const std::string& value);
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int InsertAfter(const std::string& key, const std::string& pivot,
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const std::string& value);
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/// Push / Insert value at beginning/end of the list. Return the length.
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/// May throw RedisListException
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int PushLeft(const std::string& key, const std::string& value);
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int PushRight(const std::string& key, const std::string& value);
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/// Set (list: key)[idx] = val. Return true on success, false on fail
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/// May throw RedisListException
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bool Set(const std::string& key, int32_t index, const std::string& value);
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public: // Delete / Remove / Pop / Trim
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/// Trim (list: key) so that it will only contain the indices from start..stop
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/// Returns true on success
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/// May throw RedisListException
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bool Trim(const std::string& key, int32_t start, int32_t stop);
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/// If list is empty, return false and leave *result unchanged.
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/// Else, remove the first/last elem, store it in *result, and return true
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bool PopLeft(const std::string& key, std::string* result); // First
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bool PopRight(const std::string& key, std::string* result); // Last
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/// Remove the first (or last) num occurrences of value from the list (key)
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/// Return the number of elements removed.
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/// May throw RedisListException
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int Remove(const std::string& key, int32_t num,
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const std::string& value);
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int RemoveFirst(const std::string& key, int32_t num,
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const std::string& value);
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int RemoveLast(const std::string& key, int32_t num,
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const std::string& value);
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private: // Private Functions
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/// Calls InsertBefore or InsertAfter
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int Insert(const std::string& key, const std::string& pivot,
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const std::string& value, bool insert_after);
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private:
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std::string db_name_; // The actual database name/path
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WriteOptions put_option_;
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ReadOptions get_option_;
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/// The backend rocksdb database.
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/// Map : key --> list
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/// where a list is a sequence of elements
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/// and an element is a 4-byte integer (n), followed by n bytes of data
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std::unique_ptr<DB> db_;
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};
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} // namespace rocksdb
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#endif // ROCKSDB_LITE
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