/* -*- Mode: C; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */

/** \file

 * The main memcached header holding commonly used data

 * structures and function prototypes.

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <sys/types.h>

#include <sys/socket.h>

#include <sys/time.h>

#include <netinet/in.h>

#include <event.h>

#include <netdb.h>

#include <pthread.h>

#include <unistd.h>

#include <assert.h>

#include <grp.h>

#include <signal.h>

#include "itoa_ljust.h"

#include "protocol_binary.h"

#include "cache.h"

#include "logger.h"

#ifdef EXTSTORE

#include "extstore.h"

#include "crc32c.h"

#endif

#include "sasl_defs.h"

#ifdef TLS

#include <openssl/ssl.h>

#endif

/** Maximum length of a key. */

#define KEY_MAX_LENGTH 250

/** Maximum length of a uri encoded key. */

#define KEY_MAX_URI_ENCODED_LENGTH (KEY_MAX_LENGTH  * 3 + 1)

/** Size of an incr buf. */

#define INCR_MAX_STORAGE_LEN 24

#define DATA_BUFFER_SIZE 2048

#define UDP_READ_BUFFER_SIZE 65536

#define UDP_MAX_PAYLOAD_SIZE 1400

#define UDP_HEADER_SIZE 8

#define MAX_SENDBUF_SIZE (256 * 1024 * 1024)

/* Up to 3 numbers (2 32bit, 1 64bit), spaces, newlines, null 0 */

#define SUFFIX_SIZE 50

/** Initial size of list of items being returned by "get". */

#define ITEM_LIST_INITIAL 200

/** Initial size of list of CAS suffixes appended to "gets" lines. */

#define SUFFIX_LIST_INITIAL 100

/** Initial size of the sendmsg() scatter/gather array. */

#define IOV_LIST_INITIAL 400

/** Initial number of sendmsg() argument structures to allocate. */

#define MSG_LIST_INITIAL 10

/** High water marks for buffer shrinking */

#define READ_BUFFER_HIGHWAT 8192

#define ITEM_LIST_HIGHWAT 400

#define IOV_LIST_HIGHWAT 600

#define MSG_LIST_HIGHWAT 100

/* Binary protocol stuff */

#define MIN_BIN_PKT_LENGTH 16

#define BIN_PKT_HDR_WORDS (MIN_BIN_PKT_LENGTH/sizeof(uint32_t))

/* Initial power multiplier for the hash table */

#define HASHPOWER_DEFAULT 16

#define HASHPOWER_MAX 32

/*

 * We only reposition items in the LRU queue if they haven't been repositioned

 * in this many seconds. That saves us from churning on frequently-accessed

 * items.

 */

#define ITEM_UPDATE_INTERVAL 60

/*

 * Valid range of the maximum size of an item, in bytes.

 */

#define ITEM_SIZE_MAX_LOWER_LIMIT 1024

#define ITEM_SIZE_MAX_UPPER_LIMIT 1024 * 1024 * 1024

/* unistd.h is here */

#if HAVE_UNISTD_H

# include <unistd.h>

#endif

/* Slab sizing definitions. */

#define POWER_SMALLEST 1

#define POWER_LARGEST  256 /* actual cap is 255 */

#define SLAB_GLOBAL_PAGE_POOL 0 /* magic slab class for storing pages for reassignment */

#define CHUNK_ALIGN_BYTES 8

/* slab class max is a 6-bit number, -1. */

#define MAX_NUMBER_OF_SLAB_CLASSES (63 + 1)

/** How long an object can reasonably be assumed to be locked before

    harvesting it on a low memory condition. Default: disabled. */

#define TAIL_REPAIR_TIME_DEFAULT 0

/* warning: don't use these macros with a function, as it evals its arg twice */

#define ITEM_get_cas(i) (((i)->it_flags & ITEM_CAS) ? \

        (i)->data->cas : (uint64_t)0)

#define ITEM_set_cas(i,v) { \

    if ((i)->it_flags & ITEM_CAS) { \

        (i)->data->cas = v; \

    } \

}

#define ITEM_key(item) (((char*)&((item)->data)) \

         + (((item)->it_flags & ITEM_CAS) ? sizeof(uint64_t) : 0))

#define ITEM_suffix(item) ((char*) &((item)->data) + (item)->nkey + 1 \

         + (((item)->it_flags & ITEM_CAS) ? sizeof(uint64_t) : 0))

#define ITEM_data(item) ((char*) &((item)->data) + (item)->nkey + 1 \

         + (((item)->it_flags & ITEM_CFLAGS) ? sizeof(uint32_t) : 0) \

         + (((item)->it_flags & ITEM_CAS) ? sizeof(uint64_t) : 0))

#define ITEM_ntotal(item) (sizeof(struct _stritem) + (item)->nkey + 1 \

         + (item)->nbytes \

         + (((item)->it_flags & ITEM_CFLAGS) ? sizeof(uint32_t) : 0) \

         + (((item)->it_flags & ITEM_CAS) ? sizeof(uint64_t) : 0))

#define ITEM_clsid(item) ((item)->slabs_clsid & ~(3<<6))

#define ITEM_lruid(item) ((item)->slabs_clsid & (3<<6))

#define STAT_KEY_LEN 128

#define STAT_VAL_LEN 128

/** Append a simple stat with a stat name, value format and value */

#define APPEND_STAT(name, fmt, val) \

    append_stat(name, add_stats, c, fmt, val);

/** Append an indexed stat with a stat name (with format), value format

    and value */

#define APPEND_NUM_FMT_STAT(name_fmt, num, name, fmt, val)          \

    klen = snprintf(key_str, STAT_KEY_LEN, name_fmt, num, name);    \

    vlen = snprintf(val_str, STAT_VAL_LEN, fmt, val);               \

    add_stats(key_str, klen, val_str, vlen, c);

/** Common APPEND_NUM_FMT_STAT format. */

#define APPEND_NUM_STAT(num, name, fmt, val) \

    APPEND_NUM_FMT_STAT("%d:%s", num, name, fmt, val)

/** Item client flag conversion */

#define FLAGS_CONV(it, flag) { \

    if ((it)->it_flags & ITEM_CFLAGS) { \

        flag = *((uint32_t *)ITEM_suffix((it))); \

    } else { \

        flag = 0; \

    } \

}

#define FLAGS_SIZE(item) (((item)->it_flags & ITEM_CFLAGS) ? sizeof(uint32_t) : 0)

/**

 * Callback for any function producing stats.

 *

 * @param key the stat's key

 * @param klen length of the key

 * @param val the stat's value in an ascii form (e.g. text form of a number)

 * @param vlen length of the value

 * @parm cookie magic callback cookie

 */

typedef void (*ADD_STAT)(const char *key, const uint16_t klen,

                         const char *val, const uint32_t vlen,

                         const void *cookie);

/*

 * NOTE: If you modify this table you _MUST_ update the function state_text

 */

/**

 * Possible states of a connection.

 */

enum conn_states {

    conn_listening,  /**< the socket which listens for connections */

    conn_new_cmd,    /**< Prepare connection for next command */

    conn_waiting,    /**< waiting for a readable socket */

    conn_read,       /**< reading in a command line */

    conn_parse_cmd,  /**< try to parse a command from the input buffer */

    conn_write,      /**< writing out a simple response */

    conn_nread,      /**< reading in a fixed number of bytes */

    conn_swallow,    /**< swallowing unnecessary bytes w/o storing */

    conn_closing,    /**< closing this connection */

    conn_mwrite,     /**< writing out many items sequentially */

    conn_closed,     /**< connection is closed */

    conn_watch,      /**< held by the logger thread as a watcher */

    conn_max_state   /**< Max state value (used for assertion) */

};

enum bin_substates {

    bin_no_state,

    bin_reading_set_header,

    bin_reading_cas_header,

    bin_read_set_value,

    bin_reading_get_key,

    bin_reading_stat,

    bin_reading_del_header,

    bin_reading_incr_header,

    bin_read_flush_exptime,

    bin_reading_sasl_auth,

    bin_reading_sasl_auth_data,

    bin_reading_touch_key,

};

enum protocol {

    ascii_prot = 3, /* arbitrary value. */

    binary_prot,

    negotiating_prot /* Discovering the protocol */

};

enum network_transport {

    local_transport, /* Unix sockets*/

    tcp_transport,

    udp_transport

};

enum pause_thread_types {

    PAUSE_WORKER_THREADS = 0,

    PAUSE_ALL_THREADS,

    RESUME_ALL_THREADS,

    RESUME_WORKER_THREADS

};

enum stop_reasons {

    NOT_STOP,

    GRACE_STOP,

    EXIT_NORMALLY

};

#define IS_TCP(x) (x == tcp_transport)

#define IS_UDP(x) (x == udp_transport)

#define NREAD_ADD 1

#define NREAD_SET 2

#define NREAD_REPLACE 3

#define NREAD_APPEND 4

#define NREAD_PREPEND 5

#define NREAD_CAS 6

enum store_item_type {

    NOT_STORED=0, STORED, EXISTS, NOT_FOUND, TOO_LARGE, NO_MEMORY

};

enum delta_result_type {

    OK, NON_NUMERIC, EOM, DELTA_ITEM_NOT_FOUND, DELTA_ITEM_CAS_MISMATCH

};

/** Time relative to server start. Smaller than time_t on 64-bit systems. */

// TODO: Move to sub-header. needed in logger.h

//typedef unsigned int rel_time_t;

/** Use X macros to avoid iterating over the stats fields during reset and

 * aggregation. No longer have to add new stats in 3+ places.

 */

#define SLAB_STATS_FIELDS \

    X(set_cmds) \

    X(get_hits) \

    X(touch_hits) \

    X(delete_hits) \

    X(cas_hits) \

    X(cas_badval) \

    X(incr_hits) \

    X(decr_hits)

/** Stats stored per slab (and per thread). */

struct slab_stats {

#define X(name) uint64_t    name;

    SLAB_STATS_FIELDS

#undef X

};

#define THREAD_STATS_FIELDS \

    X(get_cmds) \

    X(get_misses) \

    X(get_expired) \

    X(get_flushed) \

    X(touch_cmds) \

    X(touch_misses) \

    X(delete_misses) \

    X(incr_misses) \

    X(decr_misses) \

    X(cas_misses) \

    X(meta_cmds) \

    X(bytes_read) \

    X(bytes_written) \

    X(flush_cmds) \

    X(conn_yields) /* # of yields for connections (-R option)*/ \

    X(auth_cmds) \

    X(auth_errors) \

    X(idle_kicks) /* idle connections killed */

#ifdef EXTSTORE

#define EXTSTORE_THREAD_STATS_FIELDS \

    X(get_extstore) \

    X(get_aborted_extstore) \

    X(get_oom_extstore) \

    X(recache_from_extstore) \

    X(miss_from_extstore) \

    X(badcrc_from_extstore)

#endif

/**

 * Stats stored per-thread.

 */

struct thread_stats {

    pthread_mutex_t   mutex;

#define X(name) uint64_t    name;

    THREAD_STATS_FIELDS

#ifdef EXTSTORE

    EXTSTORE_THREAD_STATS_FIELDS

#endif

#undef X

    struct slab_stats slab_stats[MAX_NUMBER_OF_SLAB_CLASSES];

    uint64_t lru_hits[POWER_LARGEST];

};

/**

 * Global stats. Only resettable stats should go into this structure.

 */

struct stats {

    uint64_t      total_items;

    uint64_t      total_conns;

    uint64_t      rejected_conns;

    uint64_t      malloc_fails;

    uint64_t      listen_disabled_num;

    uint64_t      slabs_moved;       /* times slabs were moved around */

    uint64_t      slab_reassign_rescues; /* items rescued during slab move */

    uint64_t      slab_reassign_evictions_nomem; /* valid items lost during slab move */

    uint64_t      slab_reassign_inline_reclaim; /* valid items lost during slab move */

    uint64_t      slab_reassign_chunk_rescues; /* chunked-item chunks recovered */

    uint64_t      slab_reassign_busy_items; /* valid temporarily unmovable */

    uint64_t      slab_reassign_busy_deletes; /* refcounted items killed */

    uint64_t      lru_crawler_starts; /* Number of item crawlers kicked off */

    uint64_t      lru_maintainer_juggles; /* number of LRU bg pokes */

    uint64_t      time_in_listen_disabled_us;  /* elapsed time in microseconds while server unable to process new connections */

    uint64_t      log_worker_dropped; /* logs dropped by worker threads */

    uint64_t      log_worker_written; /* logs written by worker threads */

    uint64_t      log_watcher_skipped; /* logs watchers missed */

    uint64_t      log_watcher_sent; /* logs sent to watcher buffers */

#ifdef EXTSTORE

    uint64_t      extstore_compact_lost; /* items lost because they were locked */

    uint64_t      extstore_compact_rescues; /* items re-written during compaction */

    uint64_t      extstore_compact_skipped; /* unhit items skipped during compaction */

#endif

    struct timeval maxconns_entered;  /* last time maxconns entered */

};

/**

 * Global "state" stats. Reflects state that shouldn't be wiped ever.

 * Ordered for some cache line locality for commonly updated counters.

 */

struct stats_state {

    uint64_t      curr_items;

    uint64_t      curr_bytes;

    uint64_t      curr_conns;

    uint64_t      hash_bytes;       /* size used for hash tables */

    unsigned int  conn_structs;

    unsigned int  reserved_fds;

    unsigned int  hash_power_level; /* Better hope it's not over 9000 */

    bool          hash_is_expanding; /* If the hash table is being expanded */

    bool          accepting_conns;  /* whether we are currently accepting */

    bool          slab_reassign_running; /* slab reassign in progress */

    bool          lru_crawler_running; /* crawl in progress */

};

#define MAX_VERBOSITY_LEVEL 2

/* When adding a setting, be sure to update process_stat_settings */

/**

 * Globally accessible settings as derived from the commandline.

 */

struct settings {

    size_t maxbytes;

    int maxconns;

    int port;

    int udpport;

    char *inter;

    int verbose;

    rel_time_t oldest_live; /* ignore existing items older than this */

    uint64_t oldest_cas; /* ignore existing items with CAS values lower than this */

    int evict_to_free;

    char *socketpath;   /* path to unix socket if using local socket */

    char *auth_file;    /* path to user authentication file */

    int access;  /* access mask (a la chmod) for unix domain socket */

    double factor;          /* chunk size growth factor */

    int chunk_size;

    int num_threads;        /* number of worker (without dispatcher) libevent threads to run */

    int num_threads_per_udp; /* number of worker threads serving each udp socket */

    char prefix_delimiter;  /* character that marks a key prefix (for stats) */

    int detail_enabled;     /* nonzero if we're collecting detailed stats */

    int reqs_per_event;     /* Maximum number of io to process on each

                               io-event. */

    bool use_cas;

    enum protocol binding_protocol;

    int backlog;

    int item_size_max;        /* Maximum item size */

    int slab_chunk_size_max;  /* Upper end for chunks within slab pages. */

    int slab_page_size;     /* Slab's page units. */

    volatile sig_atomic_t sig_hup;  /* a HUP signal was received but not yet handled */

    bool sasl;              /* SASL on/off */

    bool maxconns_fast;     /* Whether or not to early close connections */

    bool lru_crawler;        /* Whether or not to enable the autocrawler thread */

    bool lru_maintainer_thread; /* LRU maintainer background thread */

    bool lru_segmented;     /* Use split or flat LRU's */

    bool slab_reassign;     /* Whether or not slab reassignment is allowed */

    int slab_automove;     /* Whether or not to automatically move slabs */

    double slab_automove_ratio; /* youngest must be within pct of oldest */

    unsigned int slab_automove_window; /* window mover for algorithm */

    int hashpower_init;     /* Starting hash power level */

    bool shutdown_command; /* allow shutdown command */

    int tail_repair_time;   /* LRU tail refcount leak repair time */

    bool flush_enabled;     /* flush_all enabled */

    bool dump_enabled;      /* whether cachedump/metadump commands work */

    char *hash_algorithm;     /* Hash algorithm in use */

    int lru_crawler_sleep;  /* Microsecond sleep between items */

    uint32_t lru_crawler_tocrawl; /* Number of items to crawl per run */

    int hot_lru_pct; /* percentage of slab space for HOT_LRU */

    int warm_lru_pct; /* percentage of slab space for WARM_LRU */

    double hot_max_factor; /* HOT tail age relative to COLD tail */

    double warm_max_factor; /* WARM tail age relative to COLD tail */

    int crawls_persleep; /* Number of LRU crawls to run before sleeping */

    bool temp_lru; /* TTL < temporary_ttl uses TEMP_LRU */

    uint32_t temporary_ttl; /* temporary LRU threshold */

    int idle_timeout;       /* Number of seconds to let connections idle */

    unsigned int logger_watcher_buf_size; /* size of logger's per-watcher buffer */

    unsigned int logger_buf_size; /* size of per-thread logger buffer */

    bool drop_privileges;   /* Whether or not to drop unnecessary process privileges */

    bool watch_enabled; /* allows watch commands to be dropped */

    bool relaxed_privileges;   /* Relax process restrictions when running testapp */

#ifdef EXTSTORE

    unsigned int ext_io_threadcount; /* number of IO threads to run. */

    unsigned int ext_page_size; /* size in megabytes of storage pages. */

    unsigned int ext_item_size; /* minimum size of items to store externally */

    unsigned int ext_item_age; /* max age of tail item before storing ext. */

    unsigned int ext_low_ttl; /* remaining TTL below this uses own pages */

    unsigned int ext_recache_rate; /* counter++ % recache_rate == 0 > recache */

    unsigned int ext_wbuf_size; /* read only note for the engine */

    unsigned int ext_compact_under; /* when fewer than this many pages, compact */

    unsigned int ext_drop_under; /* when fewer than this many pages, drop COLD items */

    double ext_max_frag; /* ideal maximum page fragmentation */

    double slab_automove_freeratio; /* % of memory to hold free as buffer */

    bool ext_drop_unread; /* skip unread items during compaction */

    /* per-slab-class free chunk limit */

    unsigned int ext_free_memchunks[MAX_NUMBER_OF_SLAB_CLASSES];

#endif

#ifdef TLS

    bool ssl_enabled; /* indicates whether SSL is enabled */

    SSL_CTX *ssl_ctx; /* holds the SSL server context which has the server certificate */

    char *ssl_chain_cert; /* path to the server SSL chain certificate */

    char *ssl_key; /* path to the server key */

    int ssl_verify_mode; /* client certificate verify mode */

    int ssl_keyformat; /* key format , defult is PEM */

    char *ssl_ciphers; /* list of SSL ciphers */

    char *ssl_ca_cert; /* certificate with CAs. */

    rel_time_t ssl_last_cert_refresh_time; /* time of the last server certificate refresh */

    unsigned int ssl_wbuf_size; /* size of the write buffer used by ssl_sendmsg method */

#endif

};

extern struct stats stats;

extern struct stats_state stats_state;

extern time_t process_started;

extern struct settings settings;

#define ITEM_LINKED 1

#define ITEM_CAS 2

/* temp */

#define ITEM_SLABBED 4

/* Item was fetched at least once in its lifetime */

#define ITEM_FETCHED 8

/* Appended on fetch, removed on LRU shuffling */

#define ITEM_ACTIVE 16

/* If an item's storage are chained chunks. */

#define ITEM_CHUNKED 32

#define ITEM_CHUNK 64

/* ITEM_data bulk is external to item */

#define ITEM_HDR 128

/* additional 4 bytes for item client flags */

#define ITEM_CFLAGS 256

/* item has sent out a token already */

#define ITEM_TOKEN_SENT 512

/* reserved, in case tokens should be a 2-bit count in future */

#define ITEM_TOKEN_RESERVED 1024

/* if item has been marked as a stale value */

#define ITEM_STALE 2048

/**

 * Structure for storing items within memcached.

 */

typedef struct _stritem {

    /* Protected by LRU locks */

    struct _stritem *next;

    struct _stritem *prev;

    /* Rest are protected by an item lock */

    struct _stritem *h_next;    /* hash chain next */

    rel_time_t      time;       /* least recent access */

    rel_time_t      exptime;    /* expire time */

    int             nbytes;     /* size of data */

    unsigned short  refcount;

    uint16_t        it_flags;   /* ITEM_* above */

    uint8_t         slabs_clsid;/* which slab class we're in */

    uint8_t         nkey;       /* key length, w/terminating null and padding */

    /* this odd type prevents type-punning issues when we do

     * the little shuffle to save space when not using CAS. */

    union {

        uint64_t cas;

        char end;

    } data[];

    /* if it_flags & ITEM_CAS we have 8 bytes CAS */

    /* then null-terminated key */

    /* then " flags length\r\n" (no terminating null) */

    /* then data with terminating \r\n (no terminating null; it's binary!) */

} item;

// TODO: If we eventually want user loaded modules, we can't use an enum :(

enum crawler_run_type {

    CRAWLER_AUTOEXPIRE=0, CRAWLER_EXPIRED, CRAWLER_METADUMP

};

typedef struct {

    struct _stritem *next;

    struct _stritem *prev;

    struct _stritem *h_next;    /* hash chain next */

    rel_time_t      time;       /* least recent access */

    rel_time_t      exptime;    /* expire time */

    int             nbytes;     /* size of data */

    unsigned short  refcount;

    uint16_t        it_flags;   /* ITEM_* above */

    uint8_t         slabs_clsid;/* which slab class we're in */

    uint8_t         nkey;       /* key length, w/terminating null and padding */

    uint32_t        remaining;  /* Max keys to crawl per slab per invocation */

    uint64_t        reclaimed;  /* items reclaimed during this crawl. */

    uint64_t        unfetched;  /* items reclaimed unfetched during this crawl. */

    uint64_t        checked;    /* items examined during this crawl. */

} crawler;

/* Header when an item is actually a chunk of another item. */

typedef struct _strchunk {

    struct _strchunk *next;     /* points within its own chain. */

    struct _strchunk *prev;     /* can potentially point to the head. */

    struct _stritem  *head;     /* always points to the owner chunk */

    int              size;      /* available chunk space in bytes */

    int              used;      /* chunk space used */

    int              nbytes;    /* used. */

    unsigned short   refcount;  /* used? */

    uint16_t         it_flags;  /* ITEM_* above. */

    uint8_t          slabs_clsid; /* Same as above. */

    uint8_t          orig_clsid; /* For obj hdr chunks slabs_clsid is fake. */

    char data[];

} item_chunk;

#ifdef NEED_ALIGN

static inline char *ITEM_schunk(item *it) {

    int offset = it->nkey + 1

        + ((it->it_flags & ITEM_CFLAGS) ? sizeof(uint32_t) : 0)

        + ((it->it_flags & ITEM_CAS) ? sizeof(uint64_t) : 0);

    int remain = offset % 8;

    if (remain != 0) {

        offset += 8 - remain;

    }

    return ((char *) &(it->data)) + offset;

}

#else

#define ITEM_schunk(item) ((char*) &((item)->data) + (item)->nkey + 1 \

         + (((item)->it_flags & ITEM_CFLAGS) ? sizeof(uint32_t) : 0) \

         + (((item)->it_flags & ITEM_CAS) ? sizeof(uint64_t) : 0))

#endif

#ifdef EXTSTORE

typedef struct {

    unsigned int page_version; /* from IO header */

    unsigned int offset; /* from IO header */

    unsigned short page_id; /* from IO header */

} item_hdr;

#endif

typedef struct {

    pthread_t thread_id;        /* unique ID of this thread */

    struct event_base *base;    /* libevent handle this thread uses */

    struct event notify_event;  /* listen event for notify pipe */

    int notify_receive_fd;      /* receiving end of notify pipe */

    int notify_send_fd;         /* sending end of notify pipe */

    struct thread_stats stats;  /* Stats generated by this thread */

    struct conn_queue *new_conn_queue; /* queue of new connections to handle */

    cache_t *suffix_cache;      /* suffix cache */

#ifdef EXTSTORE

    cache_t *io_cache;          /* IO objects */

    void *storage;              /* data object for storage system */

#endif

    logger *l;                  /* logger buffer */

    void *lru_bump_buf;         /* async LRU bump buffer */

#ifdef TLS

    char   *ssl_wbuf;

#endif

} LIBEVENT_THREAD;

typedef struct conn conn;

#ifdef EXTSTORE

typedef struct _io_wrap {

    obj_io io;

    struct _io_wrap *next;

    conn *c;

    item *hdr_it;             /* original header item. */

    unsigned int iovec_start; /* start of the iovecs for this IO */

    unsigned int iovec_count; /* total number of iovecs */

    unsigned int iovec_data;  /* specific index of data iovec */

    bool miss;                /* signal a miss to unlink hdr_it */

    bool badcrc;              /* signal a crc failure */

    bool active;              /* tells if IO was dispatched or not */

} io_wrap;

#endif

/**

 * The structure representing a connection into memcached.

 */

struct conn {

    sasl_conn_t *sasl_conn;

    int    sfd;

    bool sasl_started;

    bool authenticated;

    bool set_stale;

    bool mset_res; /** uses mset format for return code */

#ifdef TLS

    SSL    *ssl;

    char   *ssl_wbuf;

    bool ssl_enabled;

#endif

    enum conn_states  state;

    enum bin_substates substate;

    rel_time_t last_cmd_time;

    struct event event;

    short  ev_flags;

    short  which;   /** which events were just triggered */

    char   *rbuf;   /** buffer to read commands into */

    char   *rcurr;  /** but if we parsed some already, this is where we stopped */

    int    rsize;   /** total allocated size of rbuf */

    int    rbytes;  /** how much data, starting from rcur, do we have unparsed */

    char   *wbuf;

    char   *wcurr;

    int    wsize;

    int    wbytes;

    /** which state to go into after finishing current write */

    enum conn_states  write_and_go;

    void   *write_and_free; /** free this memory after finishing writing */

    char   *ritem;  /** when we read in an item's value, it goes here */

    int    rlbytes;

    /* data for the nread state */

    /**

     * item is used to hold an item structure created after reading the command

     * line of set/add/replace commands, but before we finished reading the actual

     * data. The data is read into ITEM_data(item) to avoid extra copying.

     */

    void   *item;     /* for commands set/add/replace  */

    /* data for the swallow state */

    int    sbytes;    /* how many bytes to swallow */

    /* data for the mwrite state */

    struct iovec *iov;

    int    iovsize;   /* number of elements allocated in iov[] */

    int    iovused;   /* number of elements used in iov[] */

    struct msghdr *msglist;

    int    msgsize;   /* number of elements allocated in msglist[] */

    int    msgused;   /* number of elements used in msglist[] */

    int    msgcurr;   /* element in msglist[] being transmitted now */

    int    msgbytes;  /* number of bytes in current msg */

    item   **ilist;   /* list of items to write out */

    int    isize;

    item   **icurr;

    int    ileft;

    char   **suffixlist;

    int    suffixsize;

    char   **suffixcurr;

    int    suffixleft;

#ifdef EXTSTORE

    int io_wrapleft;

    unsigned int recache_counter;

    io_wrap *io_wraplist; /* linked list of io_wraps */

    bool io_queued; /* FIXME: debugging flag */

#endif

    enum protocol protocol;   /* which protocol this connection speaks */

    enum network_transport transport; /* what transport is used by this connection */

    /* data for UDP clients */

    int    request_id; /* Incoming UDP request ID, if this is a UDP "connection" */

    struct sockaddr_in6 request_addr; /* udp: Who sent the most recent request */

    socklen_t request_addr_size;

    unsigned char *hdrbuf; /* udp packet headers */

    int    hdrsize;   /* number of headers' worth of space is allocated */

    bool   noreply;   /* True if the reply should not be sent. */

    /* current stats command */

    struct {

        char *buffer;

        size_t size;

        size_t offset;

    } stats;

    /* Binary protocol stuff */

    /* This is where the binary header goes */

    protocol_binary_request_header binary_header;

    uint64_t cas; /* the cas to return */

    short cmd; /* current command being processed */

    int opaque;

    int keylen;

    conn   *next;     /* Used for generating a list of conn structures */

    LIBEVENT_THREAD *thread; /* Pointer to the thread object serving this connection */

    int (*try_read_command)(conn *c); /* pointer for top level input parser */

    ssize_t (*read)(conn  *c, void *buf, size_t count);

    ssize_t (*sendmsg)(conn *c, struct msghdr *msg, int flags);

    ssize_t (*write)(conn *c, void *buf, size_t count);

};

/* array of conn structures, indexed by file descriptor */

extern conn **conns;

/* current time of day (updated periodically) */

extern volatile rel_time_t current_time;

/* TODO: Move to slabs.h? */

extern volatile int slab_rebalance_signal;

struct slab_rebalance {

    void *slab_start;

    void *slab_end;

    void *slab_pos;

    int s_clsid;

    int d_clsid;

    uint32_t busy_items;

    uint32_t rescues;

    uint32_t evictions_nomem;

    uint32_t inline_reclaim;

    uint32_t chunk_rescues;

    uint32_t busy_deletes;

    uint32_t busy_loops;

    uint8_t done;

    uint8_t *completed;

};

extern struct slab_rebalance slab_rebal;

#ifdef EXTSTORE

extern void *ext_storage;

#endif

/*

 * Functions

 */

void do_accept_new_conns(const bool do_accept);

enum delta_result_type do_add_delta(conn *c, const char *key,

                                    const size_t nkey, const bool incr,

                                    const int64_t delta, char *buf,

                                    uint64_t *cas, const uint32_t hv);

enum store_item_type do_store_item(item *item, int comm, conn* c, const uint32_t hv);

conn *conn_new(const int sfd, const enum conn_states init_state, const int event_flags, const int read_buffer_size,

    enum network_transport transport, struct event_base *base, void *ssl);

void conn_worker_readd(conn *c);

extern int daemonize(int nochdir, int noclose);

#define mutex_lock(x) pthread_mutex_lock(x)

#define mutex_unlock(x) pthread_mutex_unlock(x)

#include "stats_prefix.h"

#include "slabs.h"

#include "assoc.h"

#include "items.h"

#include "crawler.h"

#include "trace.h"

#include "hash.h"

#include "util.h"

/*

 * Functions such as the libevent-related calls that need to do cross-thread

 * communication in multithreaded mode (rather than actually doing the work

 * in the current thread) are called via "dispatch_" frontends, which are

 * also #define-d to directly call the underlying code in singlethreaded mode.

 */

void memcached_thread_init(int nthreads, void *arg);

void redispatch_conn(conn *c);

void dispatch_conn_new(int sfd, enum conn_states init_state, int event_flags, int read_buffer_size,

    enum network_transport transport, void *ssl);

void sidethread_conn_close(conn *c);

/* Lock wrappers for cache functions that are called from main loop. */

enum delta_result_type add_delta(conn *c, const char *key,

                                 const size_t nkey, bool incr,

                                 const int64_t delta, char *buf,

                                 uint64_t *cas);

void accept_new_conns(const bool do_accept);

conn *conn_from_freelist(void);

bool  conn_add_to_freelist(conn *c);

void  conn_close_idle(conn *c);

item *item_alloc(char *key, size_t nkey, int flags, rel_time_t exptime, int nbytes);

#define DO_UPDATE true

#define DONT_UPDATE false

item *item_get(const char *key, const size_t nkey, conn *c, const bool do_update);

item *item_get_locked(const char *key, const size_t nkey, conn *c, const bool do_update, uint32_t *hv);

item *item_touch(const char *key, const size_t nkey, uint32_t exptime, conn *c);

int   item_link(item *it);

void  item_remove(item *it);

int   item_replace(item *it, item *new_it, const uint32_t hv);

void  item_unlink(item *it);

void item_lock(uint32_t hv);

void *item_trylock(uint32_t hv);

void item_trylock_unlock(void *arg);

void item_unlock(uint32_t hv);

void pause_threads(enum pause_thread_types type);

void stop_threads(void);

int stop_conn_timeout_thread(void);

#define refcount_incr(it) ++(it->refcount)

#define refcount_decr(it) --(it->refcount)

void STATS_LOCK(void);

void STATS_UNLOCK(void);

void threadlocal_stats_reset(void);

void threadlocal_stats_aggregate(struct thread_stats *stats);

void slab_stats_aggregate(struct thread_stats *stats, struct slab_stats *out);

/* Stat processing functions */

void append_stat(const char *name, ADD_STAT add_stats, conn *c,

                 const char *fmt, ...);

enum store_item_type store_item(item *item, int comm, conn *c);

#if HAVE_DROP_PRIVILEGES

extern void setup_privilege_violations_handler(void);

extern void drop_privileges(void);

#else

#define setup_privilege_violations_handler()

#define drop_privileges()

#endif

#if HAVE_DROP_WORKER_PRIVILEGES

extern void drop_worker_privileges(void);

#else

#define drop_worker_privileges()

#endif

/* If supported, give compiler hints for branch prediction. */

#if !defined(__GNUC__) || (__GNUC__ == 2 && __GNUC_MINOR__ < 96)

#define __builtin_expect(x, expected_value) (x)

#endif

#define likely(x)       __builtin_expect((x),1)

#define unlikely(x)     __builtin_expect((x),0)