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