apr_dbm_lmdb: Add LMDB driver for apr_dbm.

git-svn-id: https://svn.apache.org/repos/asf/apr/apr-util/branches/1.7.x@1924405 13f79535-47bb-0310-9956-ffa450edef68

Author: minfrin

dbm/apr_dbm_lmdb.c

@@ -0,0 +1,376 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "apr_strings.h"
+#define APR_WANT_MEMFUNC
+#include "apr_want.h"
+#include <stdio.h>
+
+#if APR_HAVE_STDLIB_H
+#include <stdlib.h> /* for abort() */
+#endif
+
+#include "apu.h"
+
+#if APU_HAVE_LMDB
+
+#include <lmdb.h>
+
+#include "apr_dbm_private.h"
+
+typedef struct {
+    MDB_dbi dbi;
+    MDB_cursor *cursor;
+    MDB_txn *txn;
+    MDB_env *env;
+} real_file_t;
+
+
+#define APR_DBM_LMDBMODE_RO       MDB_RDONLY
+#define APR_DBM_LMDBMODE_RWCREATE MDB_CREATE
+#define APR_DBM_LMDBMODE_RW       (MDB_RDONLY + MDB_CREATE + 1)
+#define APR_DBM_LMDBMODE_RWTRUNC  (APR_DBM_LMDBMODE_RW + 1)
+
+/* --------------------------------------------------------------------------
+**
+** UTILITY FUNCTIONS
+*/
+
+/* Map a DB error to an apr_status_t */
+static apr_status_t db2s(int dberr)
+{
+    /* MDB_* error codes are negative, which are mapped to EGENERAL;
+     * positive error codes are errno which maps directly to
+     * apr_status_t. MDB_ codes could be mapped to some status code
+     * region. */
+    return dberr < 0 ? APR_EGENERAL : dberr;
+}
+
+/* Handle the return code of an mdb_* function (dberr), store the
+ * error string for access via apr_dbm_geterror(), return translated
+ * to an apr_status_t. */
+static apr_status_t set_error(apr_dbm_t *dbm, int dberr)
+{
+    if ((dbm->errcode = dberr) == MDB_SUCCESS) {
+        dbm->errmsg = NULL;
+    }
+    else {
+        dbm->errmsg = mdb_strerror(dberr);
+    }
+
+    return db2s(dberr);
+}
+
+
+/* --------------------------------------------------------------------------
+**
+** DEFINE THE VTABLE FUNCTIONS FOR LMDB
+**
+*/
+
+#define DEFAULT_ENV_FLAGS (MDB_NOSUBDIR|MDB_NOSYNC|MDB_NOLOCK)
+
+static apr_status_t vt_lmdb_open(apr_dbm_t **pdb, const char *pathname,
+                                 apr_int32_t mode, apr_fileperms_t perm,
+                                 apr_pool_t *pool)
+{
+    real_file_t file;
+    int dbi_open_flags = 0;
+    int dbmode = 0;
+    int truncate = 0;
+
+    *pdb = NULL;
+    switch (mode) {
+    case APR_DBM_READONLY:
+        dbmode = APR_DBM_LMDBMODE_RO;
+        break;
+    case APR_DBM_READWRITE:
+        dbmode = APR_DBM_LMDBMODE_RW;
+        break;
+    case APR_DBM_RWCREATE:
+        dbi_open_flags = APR_DBM_LMDBMODE_RWCREATE;
+        break;
+    case APR_DBM_RWTRUNC:
+        truncate = APR_DBM_LMDBMODE_RWTRUNC;
+        break;
+    default:
+        return APR_EINVAL;
+    }
+
+    {
+        int dberr;
+        file.txn = NULL;
+        file.cursor = NULL;
+        file.env = NULL;
+
+        dberr = mdb_env_create(&file.env);
+        if (dberr == 0) {
+            /*   Default to 2GB map size which limits the total database
+             *   size to something reasonable. */
+            dberr = mdb_env_set_mapsize(file.env, INT32_MAX);
+        }
+
+        if (dberr == 0) {
+            dberr = mdb_env_open(file.env, pathname, dbmode | DEFAULT_ENV_FLAGS, apr_posix_perms2mode(perm));
+        }
+
+        if (dberr == 0) {
+            dberr = mdb_txn_begin(file.env, NULL, dbmode, &file.txn);
+        }
+
+        if (dberr == 0) {
+            dberr = mdb_dbi_open(file.txn, NULL, dbi_open_flags, &file.dbi);
+
+            /* if mode == APR_DBM_RWTRUNC, drop database */
+            if ((dberr == 0) && truncate) {
+                dberr = mdb_drop(file.txn, file.dbi, 0);
+                if (dberr != 0) {
+                    mdb_dbi_close(file.env, file.dbi);
+                }
+            }
+        }
+
+        if (dberr != 0) {
+            /* close the env handler */
+            if (file.env) 
+                mdb_env_close(file.env);
+
+            return db2s(dberr);
+        }
+    }
+
+    /* we have an open database... return it */
+    *pdb = apr_pcalloc(pool, sizeof(**pdb));
+    (*pdb)->pool = pool;
+    (*pdb)->type = &apr_dbm_type_lmdb;
+    (*pdb)->file = apr_pmemdup(pool, &file, sizeof(file));
+
+    /* ### register a cleanup to close the DBM? */
+
+    return APR_SUCCESS;
+}
+
+static void vt_lmdb_close(apr_dbm_t *dbm)
+{
+    real_file_t *f = dbm->file;
+
+    /* try to commit all transactions that haven't been commited yet on close */
+    if (f->txn) {
+       mdb_txn_commit(f->txn);
+       f->txn = NULL;
+       f->cursor = NULL;
+    }
+
+    if (f->cursor) {
+        mdb_cursor_close(f->cursor);
+        f->cursor = NULL;
+    }
+
+    mdb_dbi_close(f->env, f->dbi);
+    mdb_env_close(f->env);
+
+    f->env = NULL;
+    f->dbi = 0;
+}
+
+static apr_status_t vt_lmdb_fetch(apr_dbm_t *dbm, apr_datum_t key,
+                                  apr_datum_t * pvalue)
+{
+    real_file_t *f = dbm->file;
+    MDB_val ckey = { 0 };
+    MDB_val rd = { 0 };
+    int dberr;
+
+    ckey.mv_data = key.dptr;
+    ckey.mv_size = key.dsize;
+
+    dberr = mdb_get(f->txn, f->dbi, &(ckey), &(rd));
+
+    /* "not found" is not an error. return zero'd value. */
+    if (dberr == MDB_NOTFOUND) {
+        memset(&rd, 0, sizeof(rd));
+        dberr = 0;
+    }
+
+    pvalue->dptr = rd.mv_data;
+    pvalue->dsize = rd.mv_size;
+
+    /* store the error info into DBM, and return a status code. Also, note
+       that *pvalue should have been cleared on error. */
+    return set_error(dbm, dberr);
+}
+
+static apr_status_t vt_lmdb_store(apr_dbm_t *dbm, apr_datum_t key,
+                                  apr_datum_t value)
+{
+    real_file_t *f = dbm->file;
+    int rv;
+    MDB_val ckey = { 0 };
+    MDB_val cvalue = { 0 };
+
+    ckey.mv_data = key.dptr;
+    ckey.mv_size = key.dsize;
+
+    cvalue.mv_data = value.dptr;
+    cvalue.mv_size = value.dsize;
+
+    if ((rv = mdb_put(f->txn, f->dbi, &ckey, &cvalue, 0)) == 0) {
+        /* commit transaction */
+        if ((rv = mdb_txn_commit(f->txn)) == MDB_SUCCESS) {
+            f->cursor = NULL;
+            rv = mdb_txn_begin(f->env, NULL, 0, &f->txn);
+        }
+
+        /* if mdb_txn_commit OR mdb_txn_begin fails ... */
+        if (rv != MDB_SUCCESS) {
+            f->txn = NULL;
+        }
+    }
+
+    /* store any error info into DBM, and return a status code. */
+    return set_error(dbm, rv);
+}
+
+static apr_status_t vt_lmdb_del(apr_dbm_t *dbm, apr_datum_t key)
+{
+    real_file_t *f = dbm->file;
+    int rv;
+    MDB_val ckey = { 0 };
+
+    ckey.mv_data = key.dptr;
+    ckey.mv_size = key.dsize;
+
+    if ((rv = mdb_del(f->txn, f->dbi, &ckey, NULL)) == 0) {
+        /* commit transaction */
+        if ((rv = mdb_txn_commit(f->txn)) == MDB_SUCCESS) {
+            f->cursor = NULL;
+            rv = mdb_txn_begin(f->env, NULL, 0, &f->txn);
+        }
+
+        /* if mdb_txn_commit OR mdb_txn_begin fails ... */
+        if (rv != MDB_SUCCESS) {
+            f->txn = NULL;
+        }
+    }
+
+    /* store any error info into DBM, and return a status code. */
+    return set_error(dbm, rv);
+}
+
+static int vt_lmdb_exists(apr_dbm_t *dbm, apr_datum_t key)
+{
+    real_file_t *f = dbm->file;
+    MDB_val ckey = { 0 };   /* converted key */
+    MDB_val data = { 0 };
+    int dberr;
+
+    ckey.mv_data = key.dptr;
+    ckey.mv_size = key.dsize;
+
+    dberr = mdb_get(f->txn, f->dbi, &(ckey), &(data));
+
+    /* note: the result data is "loaned" to us; we don't need to free it */
+
+    /* DB returns DB_NOTFOUND if it doesn't exist. but we want to say
+       that *any* error means it doesn't exist. */
+    return dberr == 0;
+}
+
+static apr_status_t vt_lmdb_firstkey(apr_dbm_t *dbm, apr_datum_t * pkey)
+{
+    real_file_t *f = dbm->file;
+    MDB_val first, data;
+    int dberr;
+
+    if ((dberr = mdb_cursor_open(f->txn, f->dbi, &f->cursor)) == 0) {
+        dberr = mdb_cursor_get(f->cursor, &first, &data, MDB_FIRST);
+        if (dberr == MDB_NOTFOUND) {
+            memset(&first, 0, sizeof(first));
+            mdb_cursor_close(f->cursor);
+            f->cursor = NULL;
+            dberr = 0;
+        }
+    }
+    else {
+        /* clear first if mdb_cursor_open fails */
+        memset(&first, 0, sizeof(first));
+    }
+
+    pkey->dptr = first.mv_data;
+    pkey->dsize = first.mv_size;
+
+    /* store any error info into DBM, and return a status code. */
+    return set_error(dbm, dberr);
+}
+
+static apr_status_t vt_lmdb_nextkey(apr_dbm_t *dbm, apr_datum_t * pkey)
+{
+    real_file_t *f = dbm->file;
+    MDB_val ckey, data;
+    int dberr;
+
+    ckey.mv_data = pkey->dptr;
+    ckey.mv_size = pkey->dsize;
+
+    if (f->cursor == NULL) {
+        return APR_EINVAL;
+    }
+
+    dberr = mdb_cursor_get(f->cursor, &ckey, &data, MDB_NEXT);
+    if (dberr == MDB_NOTFOUND) {
+        mdb_cursor_close(f->cursor);
+        f->cursor = NULL;
+        dberr = 0;
+        ckey.mv_data = NULL;
+        ckey.mv_size = 0;
+    }
+
+    pkey->dptr = ckey.mv_data;
+    pkey->dsize = ckey.mv_size;
+
+    /* store any error info into DBM, and return a status code. */
+    return set_error(dbm, dberr);
+}
+
+static void vt_lmdb_freedatum(apr_dbm_t *dbm, apr_datum_t data)
+{
+    /* nothing to do */
+}
+
+static void vt_lmdb_usednames(apr_pool_t *pool, const char *pathname,
+                              const char **used1, const char **used2)
+{
+    *used1 = apr_pstrdup(pool, pathname);
+    *used2 = apr_pstrcat(pool, pathname, "-lock", NULL);
+}
+
+
+APU_MODULE_DECLARE_DATA const apr_dbm_driver_t apr_dbm_type_lmdb = {
+    "lmdb",
+
+    vt_lmdb_open,
+    vt_lmdb_close,
+    vt_lmdb_fetch,
+    vt_lmdb_store,
+    vt_lmdb_del,
+    vt_lmdb_exists,
+    vt_lmdb_firstkey,
+    vt_lmdb_nextkey,
+    vt_lmdb_freedatum,
+    vt_lmdb_usednames
+};
+
+#endif /* APU_HAVE_LMDB */