lmdb_rdonly4.c

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/syscall.h>
#include "lmdb.h"

#define DBDIR       "./testdb"
#define DBNAME      "name"

static MDB_env *env;
static struct db_t {
    MDB_txn *txn;
    MDB_dbi dbi;
} dbr, dbw;

static int tid(void)
{
    return (int)syscall(SYS_gettid);
}

static void db_open(struct db_t *pdb, unsigned int flags)
{
    int rc;
    MDB_envinfo stat;
    if (mdb_env_info(env, &stat) == 0) {
        fprintf(stderr, "  last txnid=%lu\n", stat.me_last_txnid);
    }

    fprintf(stderr, "  -->db_open(tid=%d)\n", tid());
    rc = mdb_txn_begin(env, NULL, flags, &pdb->txn);
    if (rc) {
        fprintf(stderr, "fail: mdb_txn_begin(%s)\n", mdb_strerror(rc));
        goto LABEL_EXIT2;
    }
    rc = mdb_dbi_open(pdb->txn, DBNAME, 0, &pdb->dbi);
    if (rc) {
        fprintf(stderr, "fail: mdb_dbi_open(%s)\n", mdb_strerror(rc));
        mdb_txn_abort(pdb->txn);
        goto LABEL_EXIT2;
    }
    fprintf(stderr, "  -->db_open exit(tid=%d)\n", tid());
LABEL_EXIT2:
    return;
}

static void db_w(void)
{
    MDB_val key, data;

    fprintf(stderr, " -->db_w(tid=%d)\n", tid());

    int code = 5;
    int slp = 30;
    key.mv_size = sizeof(code);
    key.mv_data = &code;
    data.mv_size = sizeof(slp);
    data.mv_data = &slp;
    int rc = mdb_put(dbw.txn, dbw.dbi, &key, &data, 0);
    if (rc == 0) {
        fprintf(stderr, " -->txn commit(tid=%d)\n", tid());
        mdb_txn_commit(dbw.txn);
    } else {
        fprintf(stderr, "fail: mdb_put(%s)\n", mdb_strerror(rc));
        mdb_txn_abort(dbw.txn);
    }

    fprintf(stderr, " -->db_w exit(tid=%d)\n", tid());
}

static void *thread_func_r(void *pArg)
{
    //1. open RDONLY
    fprintf(stderr, "1. open RDONLY(tid=%d)\n", (int)syscall(SYS_gettid));
    db_open(&dbr, MDB_RDONLY);
    sleep(2);

    //3. aobrt RDONLY
    fprintf(stderr, "3. abort RDONLY(tid=%d)\n", (int)syscall(SYS_gettid));
    mdb_txn_abort(dbr.txn);
    //4. open NORMAL
    fprintf(stderr, "4. open NORMAL(tid=%d)\n", (int)syscall(SYS_gettid));
    db_open(&dbr, 0);

    fprintf(stderr, "txn abort(tid=%d)\n", (int)syscall(SYS_gettid));
    mdb_txn_abort(dbr.txn);

    return NULL;
}

static void *thread_func_w(void *pArg)
{
    //2. open NORMAL
    fprintf(stderr, "2. open NORMAL(tid=%d)\n", (int)syscall(SYS_gettid));
    db_open(&dbw, 0);
    sleep(2);

    //5. put
    fprintf(stderr, "5. put(tid=%d)\n", (int)syscall(SYS_gettid));
    db_w();

    return NULL;
}

int main(void)
{
    int rc;
    MDB_txn *txn;
    MDB_dbi dbi;

    mkdir(DBDIR, 0755);

    rc = mdb_env_create(&env);
    if (rc) {
        fprintf(stderr, "fail: mdb_env_create(%s)\n", mdb_strerror(rc));
    }
    rc = mdb_env_set_maxdbs(env, 1);
    if (rc) {
        fprintf(stderr, "fail: mdb_env_set_maxdbs(%s)\n", mdb_strerror(rc));
    }
    rc = mdb_env_open(env, DBDIR, MDB_FIXEDMAP, 0664);
    if (rc) {
        fprintf(stderr, "fail: mdb_env_open(%s)\n", mdb_strerror(rc));
        goto LABEL_EXIT1;
    }
    rc = mdb_txn_begin(env, NULL, 0, &txn);
    if (rc) {
        fprintf(stderr, "fail: mdb_txn_begin(%s)\n", mdb_strerror(rc));
        goto LABEL_EXIT1;
    }
    rc = mdb_dbi_open(txn, DBNAME, MDB_CREATE, &dbi);
    if (rc) {
        fprintf(stderr, "fail: mdb_dbi_open(%s)\n", mdb_strerror(rc));
        mdb_txn_abort(txn);
        goto LABEL_EXIT1;
    }
    mdb_txn_commit(txn);

    pthread_t th1;
    pthread_create(&th1, NULL, &thread_func_r, (void *)1);

    sleep(1);

    pthread_t th2;
    pthread_create(&th2, NULL, &thread_func_w, (void *)2);

    pthread_join(th1, NULL);
    pthread_join(th2, NULL);

LABEL_EXIT1:
    mdb_env_close(env);

    return 0;
}