redict/src/redis.h

#ifndef __REDIS_H
#define __REDIS_H

#include "fmacros.h"
#include "config.h"

#if defined(__sun)
#include "solarisfixes.h"
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <limits.h>
#include <unistd.h>
#include <errno.h>
#include <inttypes.h>
#include <pthread.h>

#include "ae.h"     /* Event driven programming library */
#include "sds.h"    /* Dynamic safe strings */
#include "dict.h"   /* Hash tables */
#include "adlist.h" /* Linked lists */
#include "zmalloc.h" /* total memory usage aware version of malloc/free */
#include "anet.h"   /* Networking the easy way */
#include "zipmap.h" /* Compact string -> string data structure */
#include "ziplist.h" /* Compact list data structure */
#include "intset.h" /* Compact integer set structure */
#include "version.h"

/* Error codes */
#define REDIS_OK                0
#define REDIS_ERR               -1

/* Static server configuration */
#define REDIS_SERVERPORT        6379    /* TCP port */
#define REDIS_MAXIDLETIME       (60*5)  /* default client timeout */
#define REDIS_IOBUF_LEN         1024
#define REDIS_LOADBUF_LEN       1024
#define REDIS_STATIC_ARGS       8
#define REDIS_DEFAULT_DBNUM     16
#define REDIS_CONFIGLINE_MAX    1024
#define REDIS_MAX_SYNC_TIME     60      /* Slave can't take more to sync */
#define REDIS_EXPIRELOOKUPS_PER_CRON    10 /* lookup 10 expires per loop */
#define REDIS_MAX_WRITE_PER_EVENT (1024*64)
#define REDIS_REQUEST_MAX_SIZE (1024*1024*256) /* max bytes in inline command */
#define REDIS_SHARED_INTEGERS 10000
#define REDIS_REPLY_CHUNK_BYTES (5*1500) /* 5 TCP packets with default MTU */

/* If more then REDIS_WRITEV_THRESHOLD write packets are pending use writev */
#define REDIS_WRITEV_THRESHOLD      3
/* Max number of iovecs used for each writev call */
#define REDIS_WRITEV_IOVEC_COUNT    256

/* Hash table parameters */
#define REDIS_HT_MINFILL        10      /* Minimal hash table fill 10% */

/* Command flags:
 *   REDIS_CMD_DENYOOM:
 *     Commands marked with this flag will return an error when 'maxmemory' is
 *     set and the server is using more than 'maxmemory' bytes of memory.
 *     In short: commands with this flag are denied on low memory conditions.
 *   REDIS_CMD_FORCE_REPLICATION:
 *     Force replication even if dirty is 0. */
#define REDIS_CMD_DENYOOM 4
#define REDIS_CMD_FORCE_REPLICATION 8

/* Object types */
#define REDIS_STRING 0
#define REDIS_LIST 1
#define REDIS_SET 2
#define REDIS_ZSET 3
#define REDIS_HASH 4
#define REDIS_VMPOINTER 8

/* Objects encoding. Some kind of objects like Strings and Hashes can be
 * internally represented in multiple ways. The 'encoding' field of the object
 * is set to one of this fields for this object. */
#define REDIS_ENCODING_RAW 0     /* Raw representation */
#define REDIS_ENCODING_INT 1     /* Encoded as integer */
#define REDIS_ENCODING_HT 2      /* Encoded as hash table */
#define REDIS_ENCODING_ZIPMAP 3  /* Encoded as zipmap */
#define REDIS_ENCODING_LINKEDLIST 4 /* Encoded as regular linked list */
#define REDIS_ENCODING_ZIPLIST 5 /* Encoded as ziplist */
#define REDIS_ENCODING_INTSET 6  /* Encoded as intset */

/* Object types only used for dumping to disk */
#define REDIS_EXPIRETIME 253
#define REDIS_SELECTDB 254
#define REDIS_EOF 255

/* Defines related to the dump file format. To store 32 bits lengths for short
 * keys requires a lot of space, so we check the most significant 2 bits of
 * the first byte to interpreter the length:
 *
 * 00|000000 => if the two MSB are 00 the len is the 6 bits of this byte
 * 01|000000 00000000 =>  01, the len is 14 byes, 6 bits + 8 bits of next byte
 * 10|000000 [32 bit integer] => if it's 01, a full 32 bit len will follow
 * 11|000000 this means: specially encoded object will follow. The six bits
 *           number specify the kind of object that follows.
 *           See the REDIS_RDB_ENC_* defines.
 *
 * Lenghts up to 63 are stored using a single byte, most DB keys, and may
 * values, will fit inside. */
#define REDIS_RDB_6BITLEN 0
#define REDIS_RDB_14BITLEN 1
#define REDIS_RDB_32BITLEN 2
#define REDIS_RDB_ENCVAL 3
#define REDIS_RDB_LENERR UINT_MAX

/* When a length of a string object stored on disk has the first two bits
 * set, the remaining two bits specify a special encoding for the object
 * accordingly to the following defines: */
#define REDIS_RDB_ENC_INT8 0        /* 8 bit signed integer */
#define REDIS_RDB_ENC_INT16 1       /* 16 bit signed integer */
#define REDIS_RDB_ENC_INT32 2       /* 32 bit signed integer */
#define REDIS_RDB_ENC_LZF 3         /* string compressed with FASTLZ */

/* Virtual memory object->where field. */
#define REDIS_VM_MEMORY 0       /* The object is on memory */
#define REDIS_VM_SWAPPED 1      /* The object is on disk */
#define REDIS_VM_SWAPPING 2     /* Redis is swapping this object on disk */
#define REDIS_VM_LOADING 3      /* Redis is loading this object from disk */

/* Virtual memory static configuration stuff.
 * Check vmFindContiguousPages() to know more about this magic numbers. */
#define REDIS_VM_MAX_NEAR_PAGES 65536
#define REDIS_VM_MAX_RANDOM_JUMP 4096
#define REDIS_VM_MAX_THREADS 32
#define REDIS_THREAD_STACK_SIZE (1024*1024*4)
/* The following is the *percentage* of completed I/O jobs to process when the
 * handelr is called. While Virtual Memory I/O operations are performed by
 * threads, this operations must be processed by the main thread when completed
 * in order to take effect. */
#define REDIS_MAX_COMPLETED_JOBS_PROCESSED 1

/* Client flags */
#define REDIS_SLAVE 1       /* This client is a slave server */
#define REDIS_MASTER 2      /* This client is a master server */
#define REDIS_MONITOR 4     /* This client is a slave monitor, see MONITOR */
#define REDIS_MULTI 8       /* This client is in a MULTI context */
#define REDIS_BLOCKED 16    /* The client is waiting in a blocking operation */
#define REDIS_IO_WAIT 32    /* The client is waiting for Virtual Memory I/O */
#define REDIS_DIRTY_CAS 64  /* Watched keys modified. EXEC will fail. */
#define REDIS_CLOSE_AFTER_REPLY 128 /* Close after writing entire reply. */

/* Client request types */
#define REDIS_REQ_INLINE 1
#define REDIS_REQ_MULTIBULK 2

/* Slave replication state - slave side */
#define REDIS_REPL_NONE 0   /* No active replication */
#define REDIS_REPL_CONNECT 1    /* Must connect to master */
#define REDIS_REPL_TRANSFER 2    /* Receiving .rdb from master */
#define REDIS_REPL_CONNECTED 3  /* Connected to master */

/* Slave replication state - from the point of view of master
 * Note that in SEND_BULK and ONLINE state the slave receives new updates
 * in its output queue. In the WAIT_BGSAVE state instead the server is waiting
 * to start the next background saving in order to send updates to it. */
#define REDIS_REPL_WAIT_BGSAVE_START 3 /* master waits bgsave to start feeding it */
#define REDIS_REPL_WAIT_BGSAVE_END 4 /* master waits bgsave to start bulk DB transmission */
#define REDIS_REPL_SEND_BULK 5 /* master is sending the bulk DB */
#define REDIS_REPL_ONLINE 6 /* bulk DB already transmitted, receive updates */

/* List related stuff */
#define REDIS_HEAD 0
#define REDIS_TAIL 1

/* Sort operations */
#define REDIS_SORT_GET 0
#define REDIS_SORT_ASC 1
#define REDIS_SORT_DESC 2
#define REDIS_SORTKEY_MAX 1024

/* Log levels */
#define REDIS_DEBUG 0
#define REDIS_VERBOSE 1
#define REDIS_NOTICE 2
#define REDIS_WARNING 3

/* Anti-warning macro... */
#define REDIS_NOTUSED(V) ((void) V)

#define ZSKIPLIST_MAXLEVEL 32 /* Should be enough for 2^32 elements */
#define ZSKIPLIST_P 0.25      /* Skiplist P = 1/4 */

/* Append only defines */
#define APPENDFSYNC_NO 0
#define APPENDFSYNC_ALWAYS 1
#define APPENDFSYNC_EVERYSEC 2

/* Zip structure related defaults */
#define REDIS_HASH_MAX_ZIPMAP_ENTRIES 64
#define REDIS_HASH_MAX_ZIPMAP_VALUE 512
#define REDIS_LIST_MAX_ZIPLIST_ENTRIES 1024
#define REDIS_LIST_MAX_ZIPLIST_VALUE 32
#define REDIS_SET_MAX_INTSET_ENTRIES 4096

/* Sets operations codes */
#define REDIS_OP_UNION 0
#define REDIS_OP_DIFF 1
#define REDIS_OP_INTER 2

/* Redis maxmemory strategies */
#define REDIS_MAXMEMORY_VOLATILE_LRU 0
#define REDIS_MAXMEMORY_VOLATILE_TTL 1
#define REDIS_MAXMEMORY_VOLATILE_RANDOM 2
#define REDIS_MAXMEMORY_ALLKEYS_LRU 3
#define REDIS_MAXMEMORY_ALLKEYS_RANDOM 4
#define REDIS_MAXMEMORY_NO_EVICTION 5

/* We can print the stacktrace, so our assert is defined this way: */
#define redisAssert(_e) ((_e)?(void)0 : (_redisAssert(#_e,__FILE__,__LINE__),_exit(1)))
#define redisPanic(_e) _redisPanic(#_e,__FILE__,__LINE__),_exit(1)
void _redisAssert(char *estr, char *file, int line);
void _redisPanic(char *msg, char *file, int line);

/*-----------------------------------------------------------------------------
 * Data types
 *----------------------------------------------------------------------------*/

/* A redis object, that is a type able to hold a string / list / set */

/* The actual Redis Object */
#define REDIS_LRU_CLOCK_MAX ((1<<21)-1) /* Max value of obj->lru */
#define REDIS_LRU_CLOCK_RESOLUTION 10 /* LRU clock resolution in seconds */
typedef struct redisObject {
    unsigned type:4;
    unsigned storage:2;     /* REDIS_VM_MEMORY or REDIS_VM_SWAPPING */
    unsigned encoding:4;
    unsigned lru:22;        /* lru time (relative to server.lruclock) */
    int refcount;
    void *ptr;
    /* VM fields are only allocated if VM is active, otherwise the
     * object allocation function will just allocate
     * sizeof(redisObjct) minus sizeof(redisObjectVM), so using
     * Redis without VM active will not have any overhead. */
} robj;

/* The VM pointer structure - identifies an object in the swap file.
 *
 * This object is stored in place of the value
 * object in the main key->value hash table representing a database.
 * Note that the first fields (type, storage) are the same as the redisObject
 * structure so that vmPointer strucuters can be accessed even when casted
 * as redisObject structures.
 *
 * This is useful as we don't know if a value object is or not on disk, but we
 * are always able to read obj->storage to check this. For vmPointer
 * structures "type" is set to REDIS_VMPOINTER (even if without this field
 * is still possible to check the kind of object from the value of 'storage').*/
typedef struct vmPointer {
    unsigned type:4;
    unsigned storage:2; /* REDIS_VM_SWAPPED or REDIS_VM_LOADING */
    unsigned notused:26;
    unsigned int vtype; /* type of the object stored in the swap file */
    off_t page;         /* the page at witch the object is stored on disk */
    off_t usedpages;    /* number of pages used on disk */
} vmpointer;

/* Macro used to initalize a Redis object allocated on the stack.
 * Note that this macro is taken near the structure definition to make sure
 * we'll update it when the structure is changed, to avoid bugs like
 * bug #85 introduced exactly in this way. */
#define initStaticStringObject(_var,_ptr) do { \
    _var.refcount = 1; \
    _var.type = REDIS_STRING; \
    _var.encoding = REDIS_ENCODING_RAW; \
    _var.ptr = _ptr; \
    _var.storage = REDIS_VM_MEMORY; \
} while(0);

typedef struct redisDb {
    dict *dict;                 /* The keyspace for this DB */
    dict *expires;              /* Timeout of keys with a timeout set */
    dict *blocking_keys;        /* Keys with clients waiting for data (BLPOP) */
    dict *io_keys;              /* Keys with clients waiting for VM I/O */
    dict *watched_keys;         /* WATCHED keys for MULTI/EXEC CAS */
    int id;
} redisDb;

/* Client MULTI/EXEC state */
typedef struct multiCmd {
    robj **argv;
    int argc;
    struct redisCommand *cmd;
} multiCmd;

typedef struct multiState {
    multiCmd *commands;     /* Array of MULTI commands */
    int count;              /* Total number of MULTI commands */
} multiState;

typedef struct blockingState {
    robj **keys;            /* The key we are waiting to terminate a blocking
                             * operation such as BLPOP. Otherwise NULL. */
    int count;              /* Number of blocking keys */
    time_t timeout;         /* Blocking operation timeout. If UNIX current time
                             * is >= timeout then the operation timed out. */
    robj *target;           /* The key that should receive the element,
                             * for BRPOPLPUSH. */
} blockingState;

/* With multiplexing we need to take per-clinet state.
 * Clients are taken in a liked list. */
typedef struct redisClient {
    int fd;
    redisDb *db;
    int dictid;
    sds querybuf;
    int argc;
    robj **argv;
    int reqtype;
    int multibulklen;       /* number of multi bulk arguments left to read */
    long bulklen;           /* length of bulk argument in multi bulk request */
    list *reply;
    int sentlen;
    time_t lastinteraction; /* time of the last interaction, used for timeout */
    int flags;              /* REDIS_SLAVE | REDIS_MONITOR | REDIS_MULTI ... */
    int slaveseldb;         /* slave selected db, if this client is a slave */
    int authenticated;      /* when requirepass is non-NULL */
    int replstate;          /* replication state if this is a slave */
    int repldbfd;           /* replication DB file descriptor */
    long repldboff;         /* replication DB file offset */
    off_t repldbsize;       /* replication DB file size */
    multiState mstate;      /* MULTI/EXEC state */
    blockingState bpop;   /* blocking state */
    list *io_keys;          /* Keys this client is waiting to be loaded from the
                             * swap file in order to continue. */
    list *watched_keys;     /* Keys WATCHED for MULTI/EXEC CAS */
    dict *pubsub_channels;  /* channels a client is interested in (SUBSCRIBE) */
    list *pubsub_patterns;  /* patterns a client is interested in (SUBSCRIBE) */

    /* Response buffer */
    int bufpos;
    char buf[REDIS_REPLY_CHUNK_BYTES];
} redisClient;

struct saveparam {
    time_t seconds;
    int changes;
};

struct sharedObjectsStruct {
    robj *crlf, *ok, *err, *emptybulk, *czero, *cone, *cnegone, *pong, *space,
    *colon, *nullbulk, *nullmultibulk, *queued,
    *emptymultibulk, *wrongtypeerr, *nokeyerr, *syntaxerr, *sameobjecterr,
    *outofrangeerr, *loadingerr, *plus,
    *select0, *select1, *select2, *select3, *select4,
    *select5, *select6, *select7, *select8, *select9,
    *messagebulk, *pmessagebulk, *subscribebulk, *unsubscribebulk, *mbulk3,
    *mbulk4, *psubscribebulk, *punsubscribebulk,
    *integers[REDIS_SHARED_INTEGERS];
};

/* Global server state structure */
struct redisServer {
    pthread_t mainthread;
    int port;
    char *bindaddr;
    char *unixsocket;
    int ipfd;
    int sofd;
    redisDb *db;
    long long dirty;            /* changes to DB from the last save */
    long long dirty_before_bgsave; /* used to restore dirty on failed BGSAVE */
    list *clients;
    dict *commands;             /* Command table hahs table */
    /* RDB / AOF loading information */
    int loading;
    off_t loading_total_bytes;
    off_t loading_loaded_bytes;
    time_t loading_start_time;
    /* Fast pointers to often looked up command */
    struct redisCommand *delCommand, *multiCommand;
    list *slaves, *monitors;
    char neterr[ANET_ERR_LEN];
    aeEventLoop *el;
    int cronloops;              /* number of times the cron function run */
    time_t lastsave;                /* Unix time of last save succeeede */
    /* Fields used only for stats */
    time_t stat_starttime;          /* server start time */
    long long stat_numcommands;     /* number of processed commands */
    long long stat_numconnections;  /* number of connections received */
    long long stat_expiredkeys;     /* number of expired keys */
    long long stat_keyspace_hits;   /* number of successful lookups of keys */
    long long stat_keyspace_misses; /* number of failed lookups of keys */
    /* Configuration */
    int verbosity;
    int glueoutputbuf;
    int maxidletime;
    int dbnum;
    int daemonize;
    int appendonly;
    int appendfsync;
    int no_appendfsync_on_rewrite;
    int shutdown_asap;
    time_t lastfsync;
    int appendfd;
    int appendseldb;
    char *pidfile;
    pid_t bgsavechildpid;
    pid_t bgrewritechildpid;
    sds bgrewritebuf; /* buffer taken by parent during oppend only rewrite */
    sds aofbuf;       /* AOF buffer, written before entering the event loop */
    struct saveparam *saveparams;
    int saveparamslen;
    char *logfile;
    char *dbfilename;
    char *appendfilename;
    char *requirepass;
    int rdbcompression;
    int activerehashing;
    /* Replication related */
    int isslave;
    /* Slave specific fields */
    char *masterauth;
    char *masterhost;
    int masterport;
    redisClient *master;    /* client that is master for this slave */
    int replstate;          /* replication status if the instance is a slave */
    off_t repl_transfer_left;  /* bytes left reading .rdb  */
    int repl_transfer_s;    /* slave -> master SYNC socket */
    int repl_transfer_fd;   /* slave -> master SYNC temp file descriptor */
    char *repl_transfer_tmpfile; /* slave-> master SYNC temp file name */
    time_t repl_transfer_lastio; /* unix time of the latest read, for timeout */
    int repl_serve_stale_data; /* Serve stale data when link is down? */
    /* Limits */
    unsigned int maxclients;
    unsigned long long maxmemory;
    int maxmemory_policy;
    int maxmemory_samples;
    /* Blocked clients */
    unsigned int blpop_blocked_clients;
    unsigned int vm_blocked_clients;
    /* Sort parameters - qsort_r() is only available under BSD so we
     * have to take this state global, in order to pass it to sortCompare() */
    int sort_desc;
    int sort_alpha;
    int sort_bypattern;
    /* Virtual memory configuration */
    int vm_enabled;
    char *vm_swap_file;
    off_t vm_page_size;
    off_t vm_pages;
    unsigned long long vm_max_memory;
    /* Zip structure config */
    size_t hash_max_zipmap_entries;
    size_t hash_max_zipmap_value;
    size_t list_max_ziplist_entries;
    size_t list_max_ziplist_value;
    size_t set_max_intset_entries;
    /* Virtual memory state */
    FILE *vm_fp;
    int vm_fd;
    off_t vm_next_page; /* Next probably empty page */
    off_t vm_near_pages; /* Number of pages allocated sequentially */
    unsigned char *vm_bitmap; /* Bitmap of free/used pages */
    time_t unixtime;    /* Unix time sampled every second. */
    /* Virtual memory I/O threads stuff */
    /* An I/O thread process an element taken from the io_jobs queue and
     * put the result of the operation in the io_done list. While the
     * job is being processed, it's put on io_processing queue. */
    list *io_newjobs; /* List of VM I/O jobs yet to be processed */
    list *io_processing; /* List of VM I/O jobs being processed */
    list *io_processed; /* List of VM I/O jobs already processed */
    list *io_ready_clients; /* Clients ready to be unblocked. All keys loaded */
    pthread_mutex_t io_mutex; /* lock to access io_jobs/io_done/io_thread_job */
    pthread_mutex_t io_swapfile_mutex; /* So we can lseek + write */
    pthread_attr_t io_threads_attr; /* attributes for threads creation */
    int io_active_threads; /* Number of running I/O threads */
    int vm_max_threads; /* Max number of I/O threads running at the same time */
    /* Our main thread is blocked on the event loop, locking for sockets ready
     * to be read or written, so when a threaded I/O operation is ready to be
     * processed by the main thread, the I/O thread will use a unix pipe to
     * awake the main thread. The followings are the two pipe FDs. */
    int io_ready_pipe_read;
    int io_ready_pipe_write;
    /* Virtual memory stats */
    unsigned long long vm_stats_used_pages;
    unsigned long long vm_stats_swapped_objects;
    unsigned long long vm_stats_swapouts;
    unsigned long long vm_stats_swapins;
    /* Pubsub */
    dict *pubsub_channels; /* Map channels to list of subscribed clients */
    list *pubsub_patterns; /* A list of pubsub_patterns */
    /* Misc */
    unsigned lruclock:22;        /* clock incrementing every minute, for LRU */
    unsigned lruclock_padding:10;
};

typedef struct pubsubPattern {
    redisClient *client;
    robj *pattern;
} pubsubPattern;

typedef void redisCommandProc(redisClient *c);
typedef void redisVmPreloadProc(redisClient *c, struct redisCommand *cmd, int argc, robj **argv);
struct redisCommand {
    char *name;
    redisCommandProc *proc;
    int arity;
    int flags;
    /* Use a function to determine which keys need to be loaded
     * in the background prior to executing this command. Takes precedence
     * over vm_firstkey and others, ignored when NULL */
    redisVmPreloadProc *vm_preload_proc;
    /* What keys should be loaded in background when calling this command? */
    int vm_firstkey; /* The first argument that's a key (0 = no keys) */
    int vm_lastkey;  /* THe last argument that's a key */
    int vm_keystep;  /* The step between first and last key */
};

struct redisFunctionSym {
    char *name;
    unsigned long pointer;
};

typedef struct _redisSortObject {
    robj *obj;
    union {
        double score;
        robj *cmpobj;
    } u;
} redisSortObject;

typedef struct _redisSortOperation {
    int type;
    robj *pattern;
} redisSortOperation;

/* ZSETs use a specialized version of Skiplists */
typedef struct zskiplistNode {
    robj *obj;
    double score;
    struct zskiplistNode *backward;
    struct zskiplistLevel {
        struct zskiplistNode *forward;
        unsigned int span;
    } level[];
} zskiplistNode;

typedef struct zskiplist {
    struct zskiplistNode *header, *tail;
    unsigned long length;
    int level;
} zskiplist;

typedef struct zset {
    dict *dict;
    zskiplist *zsl;
} zset;

/* VM threaded I/O request message */
#define REDIS_IOJOB_LOAD 0          /* Load from disk to memory */
#define REDIS_IOJOB_PREPARE_SWAP 1  /* Compute needed pages */
#define REDIS_IOJOB_DO_SWAP 2       /* Swap from memory to disk */
typedef struct iojob {
    int type;   /* Request type, REDIS_IOJOB_* */
    redisDb *db;/* Redis database */
    robj *key;  /* This I/O request is about swapping this key */
    robj *id;   /* Unique identifier of this job:
                   this is the object to swap for REDIS_IOREQ_*_SWAP, or the
                   vmpointer objct for REDIS_IOREQ_LOAD. */
    robj *val;  /* the value to swap for REDIS_IOREQ_*_SWAP, otherwise this
                 * field is populated by the I/O thread for REDIS_IOREQ_LOAD. */
    off_t page; /* Swap page where to read/write the object */
    off_t pages; /* Swap pages needed to save object. PREPARE_SWAP return val */
    int canceled; /* True if this command was canceled by blocking side of VM */
    pthread_t thread; /* ID of the thread processing this entry */
} iojob;

/* Structure to hold list iteration abstraction. */
typedef struct {
    robj *subject;
    unsigned char encoding;
    unsigned char direction; /* Iteration direction */
    unsigned char *zi;
    listNode *ln;
} listTypeIterator;

/* Structure for an entry while iterating over a list. */
typedef struct {
    listTypeIterator *li;
    unsigned char *zi;  /* Entry in ziplist */
    listNode *ln;       /* Entry in linked list */
} listTypeEntry;

/* Structure to hold set iteration abstraction. */
typedef struct {
    robj *subject;
    int encoding;
    int ii; /* intset iterator */
    dictIterator *di;
} setTypeIterator;

/* Structure to hold hash iteration abstration. Note that iteration over
 * hashes involves both fields and values. Because it is possible that
 * not both are required, store pointers in the iterator to avoid
 * unnecessary memory allocation for fields/values. */
typedef struct {
    int encoding;
    unsigned char *zi;
    unsigned char *zk, *zv;
    unsigned int zklen, zvlen;

    dictIterator *di;
    dictEntry *de;
} hashTypeIterator;

#define REDIS_HASH_KEY 1
#define REDIS_HASH_VALUE 2

/*-----------------------------------------------------------------------------
 * Extern declarations
 *----------------------------------------------------------------------------*/

extern struct redisServer server;
extern struct sharedObjectsStruct shared;
extern dictType setDictType;
extern dictType zsetDictType;
extern double R_Zero, R_PosInf, R_NegInf, R_Nan;
dictType hashDictType;

/*-----------------------------------------------------------------------------
 * Functions prototypes
 *----------------------------------------------------------------------------*/

/* networking.c -- Networking and Client related operations */
redisClient *createClient(int fd);
void closeTimedoutClients(void);
void freeClient(redisClient *c);
void resetClient(redisClient *c);
void sendReplyToClient(aeEventLoop *el, int fd, void *privdata, int mask);
void sendReplyToClientWritev(aeEventLoop *el, int fd, void *privdata, int mask);
void addReply(redisClient *c, robj *obj);
void *addDeferredMultiBulkLength(redisClient *c);
void setDeferredMultiBulkLength(redisClient *c, void *node, long length);
void addReplySds(redisClient *c, sds s);
void processInputBuffer(redisClient *c);
void acceptTcpHandler(aeEventLoop *el, int fd, void *privdata, int mask);
void acceptUnixHandler(aeEventLoop *el, int fd, void *privdata, int mask);
void readQueryFromClient(aeEventLoop *el, int fd, void *privdata, int mask);
void addReplyBulk(redisClient *c, robj *obj);
void addReplyBulkCString(redisClient *c, char *s);
void acceptHandler(aeEventLoop *el, int fd, void *privdata, int mask);
void addReply(redisClient *c, robj *obj);
void addReplySds(redisClient *c, sds s);
void addReplyError(redisClient *c, char *err);
void addReplyStatus(redisClient *c, char *status);
void addReplyDouble(redisClient *c, double d);
void addReplyLongLong(redisClient *c, long long ll);
void addReplyMultiBulkLen(redisClient *c, long length);
void *dupClientReplyValue(void *o);

#ifdef __GNUC__
void addReplyErrorFormat(redisClient *c, const char *fmt, ...)
    __attribute__((format(printf, 2, 3)));
void addReplyStatusFormat(redisClient *c, const char *fmt, ...)
    __attribute__((format(printf, 2, 3)));
#else
void addReplyErrorFormat(redisClient *c, const char *fmt, ...);
void addReplyStatusFormat(redisClient *c, const char *fmt, ...);
#endif

/* List data type */
void listTypeTryConversion(robj *subject, robj *value);
void listTypePush(robj *subject, robj *value, int where);
robj *listTypePop(robj *subject, int where);
unsigned long listTypeLength(robj *subject);
listTypeIterator *listTypeInitIterator(robj *subject, int index, unsigned char direction);
void listTypeReleaseIterator(listTypeIterator *li);
int listTypeNext(listTypeIterator *li, listTypeEntry *entry);
robj *listTypeGet(listTypeEntry *entry);
void listTypeInsert(listTypeEntry *entry, robj *value, int where);
int listTypeEqual(listTypeEntry *entry, robj *o);
void listTypeDelete(listTypeEntry *entry);
void listTypeConvert(robj *subject, int enc);
void unblockClientWaitingData(redisClient *c);
int handleClientsWaitingListPush(redisClient *c, robj *key, robj *ele);
void popGenericCommand(redisClient *c, int where);

/* MULTI/EXEC/WATCH... */
void unwatchAllKeys(redisClient *c);
void initClientMultiState(redisClient *c);
void freeClientMultiState(redisClient *c);
void queueMultiCommand(redisClient *c, struct redisCommand *cmd);
void touchWatchedKey(redisDb *db, robj *key);
void touchWatchedKeysOnFlush(int dbid);

/* Redis object implementation */
void decrRefCount(void *o);
void incrRefCount(robj *o);
void freeStringObject(robj *o);
void freeListObject(robj *o);
void freeSetObject(robj *o);
void freeZsetObject(robj *o);
void freeHashObject(robj *o);
robj *createObject(int type, void *ptr);
robj *createStringObject(char *ptr, size_t len);
robj *dupStringObject(robj *o);
robj *tryObjectEncoding(robj *o);
robj *getDecodedObject(robj *o);
size_t stringObjectLen(robj *o);
robj *createStringObjectFromLongLong(long long value);
robj *createListObject(void);
robj *createZiplistObject(void);
robj *createSetObject(void);
robj *createIntsetObject(void);
robj *createHashObject(void);
robj *createZsetObject(void);
int getLongFromObjectOrReply(redisClient *c, robj *o, long *target, const char *msg);
int checkType(redisClient *c, robj *o, int type);
int getLongLongFromObjectOrReply(redisClient *c, robj *o, long long *target, const char *msg);
int getDoubleFromObjectOrReply(redisClient *c, robj *o, double *target, const char *msg);
int getLongLongFromObject(robj *o, long long *target);
char *strEncoding(int encoding);
int compareStringObjects(robj *a, robj *b);
int equalStringObjects(robj *a, robj *b);
unsigned long estimateObjectIdleTime(robj *o);

/* Synchronous I/O with timeout */
int syncWrite(int fd, char *ptr, ssize_t size, int timeout);
int syncRead(int fd, char *ptr, ssize_t size, int timeout);
int syncReadLine(int fd, char *ptr, ssize_t size, int timeout);
int fwriteBulkString(FILE *fp, char *s, unsigned long len);
int fwriteBulkDouble(FILE *fp, double d);
int fwriteBulkLongLong(FILE *fp, long long l);
int fwriteBulkObject(FILE *fp, robj *obj);

/* Replication */
void replicationFeedSlaves(list *slaves, int dictid, robj **argv, int argc);
void replicationFeedMonitors(list *monitors, int dictid, robj **argv, int argc);
int syncWithMaster(void);
void updateSlavesWaitingBgsave(int bgsaveerr);
void replicationCron(void);

/* Generic persistence functions */
void startLoading(FILE *fp);
void loadingProgress(off_t pos);
void stopLoading(void);

/* RDB persistence */
int rdbLoad(char *filename);
int rdbSaveBackground(char *filename);
void rdbRemoveTempFile(pid_t childpid);
int rdbSave(char *filename);
int rdbSaveObject(FILE *fp, robj *o);
off_t rdbSavedObjectLen(robj *o);
off_t rdbSavedObjectPages(robj *o);
robj *rdbLoadObject(int type, FILE *fp);
void backgroundSaveDoneHandler(int statloc);

/* AOF persistence */
void flushAppendOnlyFile(void);
void feedAppendOnlyFile(struct redisCommand *cmd, int dictid, robj **argv, int argc);
void aofRemoveTempFile(pid_t childpid);
int rewriteAppendOnlyFileBackground(void);
int loadAppendOnlyFile(char *filename);
void stopAppendOnly(void);
int startAppendOnly(void);
void backgroundRewriteDoneHandler(int statloc);

/* Sorted sets data type */
zskiplist *zslCreate(void);
void zslFree(zskiplist *zsl);
zskiplistNode *zslInsert(zskiplist *zsl, double score, robj *obj);

/* Core functions */
void freeMemoryIfNeeded(void);
int processCommand(redisClient *c);
void setupSigSegvAction(void);
struct redisCommand *lookupCommand(sds name);
struct redisCommand *lookupCommandByCString(char *s);
void call(redisClient *c, struct redisCommand *cmd);
int prepareForShutdown();
void redisLog(int level, const char *fmt, ...);
void usage();
void updateDictResizePolicy(void);
int htNeedsResize(dict *dict);
void oom(const char *msg);
void populateCommandTable(void);

/* Virtual Memory */
void vmInit(void);
void vmMarkPagesFree(off_t page, off_t count);
robj *vmLoadObject(robj *o);
robj *vmPreviewObject(robj *o);
int vmSwapOneObjectBlocking(void);
int vmSwapOneObjectThreaded(void);
int vmCanSwapOut(void);
void vmThreadedIOCompletedJob(aeEventLoop *el, int fd, void *privdata, int mask);
void vmCancelThreadedIOJob(robj *o);
void lockThreadedIO(void);
void unlockThreadedIO(void);
int vmSwapObjectThreaded(robj *key, robj *val, redisDb *db);
void freeIOJob(iojob *j);
void queueIOJob(iojob *j);
int vmWriteObjectOnSwap(robj *o, off_t page);
robj *vmReadObjectFromSwap(off_t page, int type);
void waitEmptyIOJobsQueue(void);
void vmReopenSwapFile(void);
int vmFreePage(off_t page);
void zunionInterBlockClientOnSwappedKeys(redisClient *c, struct redisCommand *cmd, int argc, robj **argv);
void execBlockClientOnSwappedKeys(redisClient *c, struct redisCommand *cmd, int argc, robj **argv);
int blockClientOnSwappedKeys(redisClient *c, struct redisCommand *cmd);
int dontWaitForSwappedKey(redisClient *c, robj *key);
void handleClientsBlockedOnSwappedKey(redisDb *db, robj *key);
vmpointer *vmSwapObjectBlocking(robj *val);

/* Set data type */
robj *setTypeCreate(robj *value);
int setTypeAdd(robj *subject, robj *value);
int setTypeRemove(robj *subject, robj *value);
int setTypeIsMember(robj *subject, robj *value);
setTypeIterator *setTypeInitIterator(robj *subject);
void setTypeReleaseIterator(setTypeIterator *si);
robj *setTypeNext(setTypeIterator *si);
robj *setTypeRandomElement(robj *subject);
unsigned long setTypeSize(robj *subject);
void setTypeConvert(robj *subject, int enc);

/* Hash data type */
void convertToRealHash(robj *o);
void hashTypeTryConversion(robj *subject, robj **argv, int start, int end);
void hashTypeTryObjectEncoding(robj *subject, robj **o1, robj **o2);
robj *hashTypeGet(robj *o, robj *key);
int hashTypeExists(robj *o, robj *key);
int hashTypeSet(robj *o, robj *key, robj *value);
int hashTypeDelete(robj *o, robj *key);
unsigned long hashTypeLength(robj *o);
hashTypeIterator *hashTypeInitIterator(robj *subject);
void hashTypeReleaseIterator(hashTypeIterator *hi);
int hashTypeNext(hashTypeIterator *hi);
robj *hashTypeCurrent(hashTypeIterator *hi, int what);
robj *hashTypeLookupWriteOrCreate(redisClient *c, robj *key);

/* Pub / Sub */
int pubsubUnsubscribeAllChannels(redisClient *c, int notify);
int pubsubUnsubscribeAllPatterns(redisClient *c, int notify);
void freePubsubPattern(void *p);
int listMatchPubsubPattern(void *a, void *b);

/* Utility functions */
int stringmatchlen(const char *pattern, int patternLen,
        const char *string, int stringLen, int nocase);
int stringmatch(const char *pattern, const char *string, int nocase);
long long memtoll(const char *p, int *err);
int ll2string(char *s, size_t len, long long value);
int isStringRepresentableAsLong(sds s, long *longval);
int isStringRepresentableAsLongLong(sds s, long long *longval);
int isObjectRepresentableAsLongLong(robj *o, long long *llongval);

/* Configuration */
void loadServerConfig(char *filename);
void appendServerSaveParams(time_t seconds, int changes);
void resetServerSaveParams();

/* db.c -- Keyspace access API */
int removeExpire(redisDb *db, robj *key);
void propagateExpire(redisDb *db, robj *key);
int expireIfNeeded(redisDb *db, robj *key);
time_t getExpire(redisDb *db, robj *key);
void setExpire(redisDb *db, robj *key, time_t when);
robj *lookupKey(redisDb *db, robj *key);
robj *lookupKeyRead(redisDb *db, robj *key);
robj *lookupKeyWrite(redisDb *db, robj *key);
robj *lookupKeyReadOrReply(redisClient *c, robj *key, robj *reply);
robj *lookupKeyWriteOrReply(redisClient *c, robj *key, robj *reply);
int dbAdd(redisDb *db, robj *key, robj *val);
int dbReplace(redisDb *db, robj *key, robj *val);
int dbExists(redisDb *db, robj *key);
robj *dbRandomKey(redisDb *db);
int dbDelete(redisDb *db, robj *key);
long long emptyDb();
int selectDb(redisClient *c, int id);

/* Git SHA1 */
char *redisGitSHA1(void);
char *redisGitDirty(void);

/* Commands prototypes */
void authCommand(redisClient *c);
void pingCommand(redisClient *c);
void echoCommand(redisClient *c);
void setCommand(redisClient *c);
void setnxCommand(redisClient *c);
void setexCommand(redisClient *c);
void getCommand(redisClient *c);
void delCommand(redisClient *c);
void existsCommand(redisClient *c);
void incrCommand(redisClient *c);
void decrCommand(redisClient *c);
void incrbyCommand(redisClient *c);
void decrbyCommand(redisClient *c);
void selectCommand(redisClient *c);
void randomkeyCommand(redisClient *c);
void keysCommand(redisClient *c);
void dbsizeCommand(redisClient *c);
void lastsaveCommand(redisClient *c);
void saveCommand(redisClient *c);
void bgsaveCommand(redisClient *c);
void bgrewriteaofCommand(redisClient *c);
void shutdownCommand(redisClient *c);
void moveCommand(redisClient *c);
void renameCommand(redisClient *c);
void renamenxCommand(redisClient *c);
void lpushCommand(redisClient *c);
void rpushCommand(redisClient *c);
void lpushxCommand(redisClient *c);
void rpushxCommand(redisClient *c);
void linsertCommand(redisClient *c);
void lpopCommand(redisClient *c);
void rpopCommand(redisClient *c);
void llenCommand(redisClient *c);
void lindexCommand(redisClient *c);
void lrangeCommand(redisClient *c);
void ltrimCommand(redisClient *c);
void typeCommand(redisClient *c);
void lsetCommand(redisClient *c);
void saddCommand(redisClient *c);
void sremCommand(redisClient *c);
void smoveCommand(redisClient *c);
void sismemberCommand(redisClient *c);
void scardCommand(redisClient *c);
void spopCommand(redisClient *c);
void srandmemberCommand(redisClient *c);
void sinterCommand(redisClient *c);
void sinterstoreCommand(redisClient *c);
void sunionCommand(redisClient *c);
void sunionstoreCommand(redisClient *c);
void sdiffCommand(redisClient *c);
void sdiffstoreCommand(redisClient *c);
void syncCommand(redisClient *c);
void flushdbCommand(redisClient *c);
void flushallCommand(redisClient *c);
void sortCommand(redisClient *c);
void lremCommand(redisClient *c);
void rpoplpushCommand(redisClient *c);
void infoCommand(redisClient *c);
void mgetCommand(redisClient *c);
void monitorCommand(redisClient *c);
void expireCommand(redisClient *c);
void expireatCommand(redisClient *c);
void getsetCommand(redisClient *c);
void ttlCommand(redisClient *c);
void persistCommand(redisClient *c);
void slaveofCommand(redisClient *c);
void debugCommand(redisClient *c);
void msetCommand(redisClient *c);
void msetnxCommand(redisClient *c);
void zaddCommand(redisClient *c);
void zincrbyCommand(redisClient *c);
void zrangeCommand(redisClient *c);
void zrangebyscoreCommand(redisClient *c);
void zrevrangebyscoreCommand(redisClient *c);
void zcountCommand(redisClient *c);
void zrevrangeCommand(redisClient *c);
void zcardCommand(redisClient *c);
void zremCommand(redisClient *c);
void zscoreCommand(redisClient *c);
void zremrangebyscoreCommand(redisClient *c);
void multiCommand(redisClient *c);
void execCommand(redisClient *c);
void discardCommand(redisClient *c);
void blpopCommand(redisClient *c);
void brpopCommand(redisClient *c);
void brpoplpushCommand(redisClient *c);
void appendCommand(redisClient *c);
void substrCommand(redisClient *c);
void strlenCommand(redisClient *c);
void zrankCommand(redisClient *c);
void zrevrankCommand(redisClient *c);
void hsetCommand(redisClient *c);
void hsetnxCommand(redisClient *c);
void hgetCommand(redisClient *c);
void hmsetCommand(redisClient *c);
void hmgetCommand(redisClient *c);
void hdelCommand(redisClient *c);
void hlenCommand(redisClient *c);
void zremrangebyrankCommand(redisClient *c);
void zunionstoreCommand(redisClient *c);
void zinterstoreCommand(redisClient *c);
void hkeysCommand(redisClient *c);
void hvalsCommand(redisClient *c);
void hgetallCommand(redisClient *c);
void hexistsCommand(redisClient *c);
void configCommand(redisClient *c);
void hincrbyCommand(redisClient *c);
void subscribeCommand(redisClient *c);
void unsubscribeCommand(redisClient *c);
void psubscribeCommand(redisClient *c);
void punsubscribeCommand(redisClient *c);
void publishCommand(redisClient *c);
void watchCommand(redisClient *c);
void unwatchCommand(redisClient *c);

#if defined(__GNUC__)
void *calloc(size_t count, size_t size) __attribute__ ((deprecated));
void free(void *ptr) __attribute__ ((deprecated));
void *malloc(size_t size) __attribute__ ((deprecated));
void *realloc(void *ptr, size_t size) __attribute__ ((deprecated));
#endif

#endif