ex_async.c

Show how to configure and use asynchronous operations.

/*-
 * Public Domain 2014-present MongoDB, Inc.
 * Public Domain 2008-2014 WiredTiger, Inc.
 *
 * This is free and unencumbered software released into the public domain.
 *
 * Anyone is free to copy, modify, publish, use, compile, sell, or
 * distribute this software, either in source code form or as a compiled
 * binary, for any purpose, commercial or non-commercial, and by any
 * means.
 *
 * In jurisdictions that recognize copyright laws, the author or authors
 * of this software dedicate any and all copyright interest in the
 * software to the public domain. We make this dedication for the benefit
 * of the public at large and to the detriment of our heirs and
 * successors. We intend this dedication to be an overt act of
 * relinquishment in perpetuity of all present and future rights to this
 * software under copyright law.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * ex_async.c
 *      demonstrates how to use the asynchronous API.
 */
#include <test_util.h>
 
static const char *home;
 
#if defined(_lint)
#define ATOMIC_ADD(v, val) ((v) += (val), (v))
#elif defined(_WIN32)
#define ATOMIC_ADD(v, val) (_InterlockedExchangeAdd(&(v), val) + val)
#else
#define ATOMIC_ADD(v, val) __atomic_add_fetch(&(v), val, __ATOMIC_SEQ_CST)
#endif
 
static int global_error = 0;
 
typedef struct {
    WT_ASYNC_CALLBACK iface;
    uint32_t num_keys;
} ASYNC_KEYS;
 
static int
async_callback(WT_ASYNC_CALLBACK *cb, WT_ASYNC_OP *op, int wiredtiger_error, uint32_t flags)
{
    ASYNC_KEYS *asynckey = (ASYNC_KEYS *)cb;
    WT_ASYNC_OPTYPE type;
    WT_ITEM k, v;
    const char *key, *value;
    uint64_t id;
 
    (void)flags; /* Unused */
 
    /* Retrieve the operation's WT_ASYNC_OPTYPE type. */
    type = op->get_type(op);
    /* Retrieve the operation's 64-bit identifier. */
    id = op->get_id(op);
    /* Check for a WiredTiger error. */
    if (wiredtiger_error != 0) {
        fprintf(stderr, "ID %" PRIu64 " error %d: %s\n", id, wiredtiger_error,
          wiredtiger_strerror(wiredtiger_error));
        global_error = wiredtiger_error;
        return (1);
    }
 
    /* If doing a search, retrieve the key/value pair. */
    if (type == WT_AOP_SEARCH) {
        error_check(op->get_key(op, &k));
        key = k.data;
        error_check(op->get_value(op, &v));
        value = v.data;
        ATOMIC_ADD(asynckey->num_keys, 1);
        printf("Id %" PRIu64 " got record: %s : %s\n", id, key, value);
    }
    return (0);
}
static ASYNC_KEYS ex_asynckeys = {{async_callback}, 0};
 
#define MAX_KEYS 15
 
int
main(int argc, char *argv[])
{
    WT_ASYNC_OP *op;
    WT_CONNECTION *conn;
    WT_SESSION *session;
    int i, ret;
    char k[MAX_KEYS][16], v[MAX_KEYS][16];
 
    home = example_setup(argc, argv);
 
    error_check(wiredtiger_open(
      home, NULL, "create,cache_size=100MB,async=(enabled=true,ops_max=20,threads=2)", &conn));
    error_check(conn->open_session(conn, NULL, NULL, &session));
    error_check(session->create(session, "table:async", "key_format=S,value_format=S"));
    /* Insert a set of keys asynchronously. */
    for (i = 0; i < MAX_KEYS; i++) {
        while (
          (ret = conn->async_new_op(conn, "table:async", NULL, &ex_asynckeys.iface, &op)) != 0) {
            /*
             * If we used up all the handles, pause and retry to give the workers a chance to catch
             * up.
             */
            fprintf(stderr, "asynchronous operation handle not available\n");
            if (ret == EBUSY)
                sleep(1);
            else
                return (EXIT_FAILURE);
        }
        /*
         * Set the operation's string key and value, and then do an asynchronous insert.
         */
        (void)snprintf(k[i], sizeof(k), "key%d", i);
        op->set_key(op, k[i]);
        (void)snprintf(v[i], sizeof(v), "value%d", i);
        op->set_value(op, v[i]);
        error_check(op->insert(op));
    }
 
    /* Wait for all outstanding operations to complete. */
    error_check(conn->async_flush(conn));
    /*
     * Compact a table asynchronously, limiting the run-time to 5 minutes.
     */
    error_check(conn->async_new_op(conn, "table:async", "timeout=300", &ex_asynckeys.iface, &op));
    error_check(op->compact(op));
    /* Search for the keys we just inserted, asynchronously. */
    for (i = 0; i < MAX_KEYS; i++) {
        while (
          (ret = conn->async_new_op(conn, "table:async", NULL, &ex_asynckeys.iface, &op)) != 0) {
            /*
             * If we used up all the handles, pause and retry to give the workers a chance to catch
             * up.
             */
            fprintf(stderr, "asynchronous operation handle not available\n");
            if (ret == EBUSY)
                sleep(1);
            else
                return (EXIT_FAILURE);
        }
 
        /*
         * Set the operation's string key and value, and then do an asynchronous search.
         */
        (void)snprintf(k[i], sizeof(k), "key%d", i);
        op->set_key(op, k[i]);
        error_check(op->search(op));
    }
 
    /*
     * Connection close automatically does an async_flush so it will wait for all queued search
     * operations to complete.
     */
    error_check(conn->close(conn, NULL));
 
    printf("Searched for %" PRIu32 " keys\n", ex_asynckeys.num_keys);
 
    return (EXIT_SUCCESS);
}