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/* -*- 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 "protocol_binary.h"
#include "cache.h"

#include "sasl_defs.h"

/** Maximum length of a key. */
#define KEY_MAX_LENGTH 250

/** 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)
/* I'm told the max length of a 64-bit num converted to string is 20 bytes.
* Plus a few for spaces, \r\n, \0 */
#define SUFFIX_SIZE 24

/** 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 20

/** 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))

/* unistd.h is here */
#if HAVE_UNISTD_H
# include <unistd.h>
#endif

/* Slab sizing definitions. */
#define POWER_SMALLEST 1
#define POWER_LARGEST 200
#define CHUNK_ALIGN_BYTES 8
#define DONT_PREALLOC_SLABS
#define MAX_NUMBER_OF_SLAB_CLASSES (POWER_LARGEST + 1)

/** How long an object can reasonably be assumed to be locked before
harvesting it on a low memory condition. */
#define TAIL_REPAIR_TIME (3 * 3600)

/* 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)->nsuffix \
+ (((item)->it_flags & ITEM_CAS) ? sizeof(uint64_t) : 0))

#define ITEM_ntotal(item) (sizeof(struct _stritem) + (item)->nkey + 1 \
+ (item)->nsuffix + (item)->nbytes \
+ (((item)->it_flags & ITEM_CAS) ? sizeof(uint64_t) : 0))

#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)

/**
* 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_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
};

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
};

#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
};

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. */
typedef unsigned int rel_time_t;

/** Stats stored per slab (and per thread). */
struct slab_stats {
    uint64_t set_cmds;
    uint64_t get_hits;
    uint64_t delete_hits;
    uint64_t cas_hits;
    uint64_t cas_badval;
    uint64_t incr_hits;
    uint64_t decr_hits;
};

/**
* Stats stored per-thread.
*/
struct thread_stats {
    pthread_mutex_t mutex;
    uint64_t get_cmds;
    uint64_t get_misses;
    uint64_t delete_misses;
    uint64_t incr_misses;
    uint64_t decr_misses;
    uint64_t cas_misses;
    uint64_t bytes_read;
    uint64_t bytes_written;
    uint64_t flush_cmds;
    uint64_t conn_yields; /* # of yields for connections (-R option)*/
    uint64_t auth_cmds;
    uint64_t auth_errors;
    struct slab_stats slab_stats[MAX_NUMBER_OF_SLAB_CLASSES];
};

/**
* Global stats.
*/
struct stats {
    pthread_mutex_t mutex;
    unsigned int curr_items;
    unsigned int total_items;
    uint64_t curr_bytes;
    unsigned int curr_conns;
    unsigned int total_conns;
    unsigned int conn_structs;
    uint64_t get_cmds;
    uint64_t set_cmds;
    uint64_t get_hits;
    uint64_t get_misses;
    uint64_t evictions;
    uint64_t reclaimed;
    time_t started; /* when the process was started */
    bool accepting_conns; /* whether we are currently accepting */
    uint64_t listen_disabled_num;
};

#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 */
    int evict_to_free;
    char *socketpath; /* path to unix socket if using local socket */
    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, and upper end for slabs */
    bool sasl; /* SASL on/off */
};

extern struct stats stats;
extern time_t process_started;
extern struct settings settings;

#define ITEM_LINKED 1
#define ITEM_CAS 2

/* temp */
#define ITEM_SLABBED 4

/**
* Structure for storing items within memcached.
*/
typedef struct _stritem {
    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;
    uint8_t nsuffix; /* length of flags-and-length string */
    uint8_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;

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 */
} LIBEVENT_THREAD;

typedef struct {
    pthread_t thread_id; /* unique ID of this thread */
    struct event_base *base; /* libevent handle this thread uses */
} LIBEVENT_DISPATCHER_THREAD;

/**
* The structure representing a connection into memcached.
*/
typedef struct conn conn;
struct conn {
    int sfd;
    sasl_conn_t *sasl_conn;
    enum conn_states state;
    enum bin_substates substate;
    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;

    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 request_addr; /* 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 */
};


/* current time of day (updated periodically) */
extern volatile rel_time_t current_time;

/*
* 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);
enum store_item_type do_store_item(item *item, int comm, conn* c);
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);
extern int daemonize(int nochdir, int noclose);


#include "stats.h"
#include "slabs.h"
#include "assoc.h"
#include "items.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 thread_init(int nthreads, struct event_base *main_base);
int dispatch_event_add(int thread, conn *c);
void dispatch_conn_new(int sfd, enum conn_states init_state, int event_flags, int read_buffer_size, enum network_transport transport);

/* 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, const int 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);
int is_listen_thread(void);
item *item_alloc(char *key, size_t nkey, int flags, rel_time_t exptime, int nbytes);
char *item_cachedump(const unsigned int slabs_clsid, const unsigned int limit, unsigned int *bytes);
void item_flush_expired(void);
item *item_get(const char *key, const size_t nkey);
int item_link(item *it);
void item_remove(item *it);
int item_replace(item *it, item *new_it);
void item_stats(ADD_STAT add_stats, void *c);
void item_stats_sizes(ADD_STAT add_stats, void *c);
void item_unlink(item *it);
void item_update(item *it);

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 drop_privileges(void);
#else
#define drop_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)
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