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

#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>

#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 legnth 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

/* Get a consistent bool type */
#if HAVE_STDBOOL_H
# include <stdbool.h>
#else
  typedef enum {false = 0, true = 1} bool;
#endif

#if HAVE_STDINT_H
# include <stdint.h>
#else
 typedef unsigned char uint8_t;
#endif

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

/** Time relative to server start. Smaller than time_t on 64-bit systems. */
typedef unsigned int rel_time_t;

struct stats {
    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;
    time_t started; /* when the process was started */
    uint64_t bytes_read;
    uint64_t bytes_written;
};

#define MAX_VERBOSITY_LEVEL 2

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 libevent threads to run */
    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. */
};

extern struct stats stats;
extern struct settings settings;

#define ITEM_LINKED 1
#define ITEM_DELETED 2

/* temp */
#define ITEM_SLABBED 4

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 */
    uint64_t cas_id; /* the CAS identifier */
    void * end[];
    /* 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;

#define ITEM_key(item) ((char*)&((item)->end[0]))

/* warning: don't use these macros with a function, as it evals its arg twice */
#define ITEM_suffix(item) ((char*) &((item)->end[0]) + (item)->nkey + 1)
#define ITEM_data(item) ((char*) &((item)->end[0]) + (item)->nkey + 1 + (item)->nsuffix)
#define ITEM_ntotal(item) (sizeof(struct _stritem) + (item)->nkey + 1 + (item)->nsuffix + (item)->nbytes)

enum conn_states {
    conn_listening, /** the socket which listens for connections */
    conn_read, /** reading in a command line */
    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 */
};

#define NREAD_ADD 1
#define NREAD_SET 2
#define NREAD_REPLACE 3
#define NREAD_APPEND 4
#define NREAD_PREPEND 5
#define NREAD_CAS 6

typedef struct conn conn;
struct conn {
    int sfd;
    int state;
    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;
    int write_and_go; /** which state to go into after finishing current write */
    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 */
    int item_comm; /* which one is it: 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;

    /* data for UDP clients */
    bool udp; /* is this is a UDP "connection" */
    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 */

    int binary; /* are we in binary mode */
    bool noreply; /* True if the reply should not be sent. */
    conn *next; /* Used for generating a list of conn structures */
};

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

/*
* Functions
*/

conn *do_conn_from_freelist();
bool do_conn_add_to_freelist(conn *c);
char *do_suffix_from_freelist();
bool do_suffix_add_to_freelist(char *s);
char *do_defer_delete(item *item, time_t exptime);
void do_run_deferred_deletes(void);
char *do_add_delta(conn *c, item *item, const bool incr, const int64_t delta,
                   char *buf);
int do_store_item(item *item, int comm);
conn *conn_new(const int sfd, const int init_state, const int event_flags, const int read_buffer_size, const bool is_udp, struct event_base *base);


#include "stats.h"
#include "slabs.h"
#include "assoc.h"
#include "items.h"
#include "memcached_dtrace.h"

/*
* In multithreaded mode, we wrap certain functions with lock management and
* replace the logic of some other functions. All wrapped functions have
* "mt_" and "do_" variants. In multithreaded mode, the plain version of a
* function is #define-d to the "mt_" variant, which often just grabs a
* lock and calls the "do_" function. In singlethreaded mode, the "do_"
* function is called directly.
*
* 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.
*/
#ifdef USE_THREADS

void thread_init(int nthreads, struct event_base *main_base);
int dispatch_event_add(int thread, conn *c);
void dispatch_conn_new(int sfd, int init_state, int event_flags, int read_buffer_size, int is_udp);

/* Lock wrappers for cache functions that are called from main loop. */
char *mt_add_delta(conn *c, item *item, const int incr, const int64_t delta,
                   char *buf);
void mt_assoc_move_next_bucket(void);
conn *mt_conn_from_freelist(void);
bool mt_conn_add_to_freelist(conn *c);
char *mt_suffix_from_freelist(void);
bool mt_suffix_add_to_freelist(char *s);
char *mt_defer_delete(item *it, time_t exptime);
int mt_is_listen_thread(void);
item *mt_item_alloc(char *key, size_t nkey, int flags, rel_time_t exptime, int nbytes);
char *mt_item_cachedump(const unsigned int slabs_clsid, const unsigned int limit, unsigned int *bytes);
void mt_item_flush_expired(void);
item *mt_item_get_notedeleted(const char *key, const size_t nkey, bool *delete_locked);
int mt_item_link(item *it);
void mt_item_remove(item *it);
int mt_item_replace(item *it, item *new_it);
char *mt_item_stats(int *bytes);
char *mt_item_stats_sizes(int *bytes);
void mt_item_unlink(item *it);
void mt_item_update(item *it);
void mt_run_deferred_deletes(void);
void *mt_slabs_alloc(size_t size, unsigned int id);
void mt_slabs_free(void *ptr, size_t size, unsigned int id);
int mt_slabs_reassign(unsigned char srcid, unsigned char dstid);
char *mt_slabs_stats(int *buflen);
void mt_stats_lock(void);
void mt_stats_unlock(void);
int mt_store_item(item *item, int comm);


# define add_delta(c,x,y,z,a) mt_add_delta(c,x,y,z,a)
# define assoc_move_next_bucket() mt_assoc_move_next_bucket()
# define conn_from_freelist() mt_conn_from_freelist()
# define conn_add_to_freelist(x) mt_conn_add_to_freelist(x)
# define suffix_from_freelist() mt_suffix_from_freelist()
# define suffix_add_to_freelist(x) mt_suffix_add_to_freelist(x)
# define defer_delete(x,y) mt_defer_delete(x,y)
# define is_listen_thread() mt_is_listen_thread()
# define item_alloc(x,y,z,a,b) mt_item_alloc(x,y,z,a,b)
# define item_cachedump(x,y,z) mt_item_cachedump(x,y,z)
# define item_flush_expired() mt_item_flush_expired()
# define item_get_notedeleted(x,y,z) mt_item_get_notedeleted(x,y,z)
# define item_link(x) mt_item_link(x)
# define item_remove(x) mt_item_remove(x)
# define item_replace(x,y) mt_item_replace(x,y)
# define item_stats(x) mt_item_stats(x)
# define item_stats_sizes(x) mt_item_stats_sizes(x)
# define item_update(x) mt_item_update(x)
# define item_unlink(x) mt_item_unlink(x)
# define run_deferred_deletes() mt_run_deferred_deletes()
# define slabs_alloc(x,y) mt_slabs_alloc(x,y)
# define slabs_free(x,y,z) mt_slabs_free(x,y,z)
# define slabs_reassign(x,y) mt_slabs_reassign(x,y)
# define slabs_stats(x) mt_slabs_stats(x)
# define store_item(x,y) mt_store_item(x,y)

# define STATS_LOCK() mt_stats_lock()
# define STATS_UNLOCK() mt_stats_unlock()

#else /* !USE_THREADS */

# define add_delta(c,x,y,z,a) do_add_delta(c,x,y,z,a)
# define assoc_move_next_bucket() do_assoc_move_next_bucket()
# define conn_from_freelist() do_conn_from_freelist()
# define conn_add_to_freelist(x) do_conn_add_to_freelist(x)
# define suffix_from_freelist() do_suffix_from_freelist()
# define suffix_add_to_freelist(x) do_suffix_add_to_freelist(x)
# define defer_delete(x,y) do_defer_delete(x,y)
# define dispatch_conn_new(x,y,z,a,b) conn_new(x,y,z,a,b,main_base)
# define dispatch_event_add(t,c) event_add(&(c)->event, 0)
# define is_listen_thread() 1
# define item_alloc(x,y,z,a,b) do_item_alloc(x,y,z,a,b)
# define item_cachedump(x,y,z) do_item_cachedump(x,y,z)
# define item_flush_expired() do_item_flush_expired()
# define item_get_notedeleted(x,y,z) do_item_get_notedeleted(x,y,z)
# define item_link(x) do_item_link(x)
# define item_remove(x) do_item_remove(x)
# define item_replace(x,y) do_item_replace(x,y)
# define item_stats(x) do_item_stats(x)
# define item_stats_sizes(x) do_item_stats_sizes(x)
# define item_unlink(x) do_item_unlink(x)
# define item_update(x) do_item_update(x)
# define run_deferred_deletes() do_run_deferred_deletes()
# define slabs_alloc(x,y) do_slabs_alloc(x,y)
# define slabs_free(x,y,z) do_slabs_free(x,y,z)
# define slabs_reassign(x,y) do_slabs_reassign(x,y)
# define slabs_stats(x) do_slabs_stats(x)
# define store_item(x,y) do_store_item(x,y)
# define thread_init(x,y) 0

# define STATS_LOCK() /**/
# define STATS_UNLOCK() /**/

#endif /* !USE_THREADS */

/* 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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