Version 3.1.1
ex_async.c

Show how to configure and use asynchronous operations.

/*-
* Public Domain 2014-2018 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) __sync_add_and_fetch(&(v), val)
#endif
static int global_error = 0;
typedef struct {
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_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_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);
}