Zookeeper c client 实现概述


// zookeeper-3.4.10/src/c/src/zk_adaptor.h
struct _zhandle {
    int fd; /* the descriptor used to talk to zookeeper */
    char *hostname; /* the hostname of zookeeper */
    struct sockaddr_storage *addrs; /* the addresses that correspond to the hostname */
    int addrs_count; /* The number of addresses in the addrs array */
    watcher_fn watcher; /* the registered watcher */
    struct timeval last_recv; /* The time that the last message was received */
    struct timeval last_send; /* The time that the last message was sent */
    struct timeval last_ping; /* The time that the last PING was sent */
    struct timeval next_deadline; /* The time of the next deadline */
    int recv_timeout; /* The maximum amount of time that can go by without 
     receiving anything from the zookeeper server */
    buffer_list_t *input_buffer; /* the current buffer being read in */
    buffer_head_t to_process; /* The buffers that have been read and are ready to be processed. */
    buffer_head_t to_send; /* The packets queued to send */
    completion_head_t sent_requests; /* The outstanding requests */
    completion_head_t completions_to_process; /* completions that are ready to run */
    int connect_index; /* The index of the address to connect to */
    clientid_t client_id;
    long long last_zxid;
    int outstanding_sync; /* Number of outstanding synchronous requests */
    struct _buffer_list primer_buffer; /* The buffer used for the handshake at the start of a connection */
    struct prime_struct primer_storage; /* the connect response */
    char primer_storage_buffer[40]; /* the true size of primer_storage */
    volatile int state;
    void *context;
    auth_list_head_t auth_h; /* authentication data list */
    /* zookeeper_close is not reentrant because it de-allocates the zhandler. 
     * This guard variable is used to defer the destruction of zhandle till 
     * right before top-level API call returns to the caller */
    int32_t ref_counter;
    volatile int close_requested;
    void *adaptor_priv;
    /* Used for debugging only: non-zero value indicates the time when the zookeeper_process
     * call returned while there was at least one unprocessed server response 
     * available in the socket recv buffer */
    struct timeval socket_readable;
    zk_hashtable* active_node_watchers;   
    zk_hashtable* active_exist_watchers;
    zk_hashtable* active_child_watchers;
    /** used for chroot path at the client side **/
    char *chroot;

/* this is used by mt_adaptor internally for thread management */
struct adaptor_threads {
     pthread_t io;
     pthread_t completion;
     int threadsToWait;         // barrier
     pthread_cond_t cond;       // barrier's conditional
     pthread_mutex_t lock;      // ... and a lock
     pthread_mutex_t zh_lock;   // critical section lock
     int self_pipe[2];

// zookeeper-3.4.10/src/c/src/zookeeper.c
typedef struct _completion_list {
    int xid;
    completion_t c;
    const void *data;
    buffer_list_t *buffer;
    struct _completion_list *next;
    watcher_registration_t* watcher;
} completion_list_t;




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