Database contexts, the toplevel structure of the API

db/db_ctx.c

@@ -0,0 +1,270 @@
+/* 
+ * $Id$ 
+ *
+ * Copyright (C) 2001-2003 FhG FOKUS
+ * Copyright (C) 2006-2007 iptelorg GmbH
+ *
+ * This file is part of ser, a free SIP server.
+ *
+ * ser is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version
+ *
+ * For a license to use the ser software under conditions
+ * other than those described here, or to purchase support for this
+ * software, please contact iptel.org by e-mail at the following addresses:
+ *    [email protected]
+ *
+ * ser is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License 
+ * along with this program; if not, write to the Free Software 
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <string.h>
+#include "../dprint.h"
+#include "../mem/mem.h"
+#include "db.h"
+#include "db_ctx.h"
+
+
+static struct db_ctx_data* db_ctx_data(str* module, db_drv_t* data)
+{
+	struct db_ctx_data* res;
+
+	res = (struct db_ctx_data*)pkg_malloc(sizeof(struct db_ctx_data));
+	if (res == NULL) goto error;
+	memset(res, '\0', sizeof(struct db_ctx_data));
+
+	res->module.s = pkg_malloc(module->len);
+	if (res->module.s == NULL) goto error;
+
+	memcpy(res->module.s, module->s, module->len);
+	res->module.len = module->len;
+	res->data = data;
+
+	return res;
+
+ error:
+	ERR("db_ctx_data: No memory left\n");
+	if (res) pkg_free(res);
+	return NULL;
+}
+
+
+static void db_ctx_data_free(struct db_ctx_data* ptr)
+{
+	if (ptr->module.s) pkg_free(ptr->module.s);
+	pkg_free(ptr);
+}
+
+
+
+/*
+ * Create a new database context
+ */
+db_ctx_t* db_ctx(const char* id)
+{
+    db_ctx_t* r;
+
+    r = (db_ctx_t*)pkg_malloc(sizeof(db_ctx_t));
+    if (r == NULL) goto error;
+    memset(r, '\0', sizeof(db_ctx_t));
+	if (db_gen_init(&r->gen) < 0) goto error;
+
+	DBLIST_INIT(&r->con);
+
+	r->id.len = strlen(id);
+	r->id.s = pkg_malloc(r->id.len + 1);
+	if (r->id.s == NULL) goto error;
+	memcpy(r->id.s, id, r->id.len + 1);
+
+	/* Insert the newly created context into the linked list
+	 * of all existing contexts
+	 */
+	DBLIST_INSERT_HEAD(&db, r);
+    return r;
+
+ error:
+	if (r) {
+		db_gen_free(&r->gen);
+		if (r->id.s) pkg_free(r->id.s);
+		pkg_free(r);
+	}
+	return NULL;
+}
+
+
+/* Remove the database context structure
+ * from the linked list and free all memory
+ * used by the structure
+ */
+void db_ctx_free(db_ctx_t* ctx)
+{
+	db_con_t* con, *tmp_con;
+	struct db_ctx_data* ptr, *ptr2;
+
+    if (ctx == NULL) return;
+
+	/* Remove the context from the linked list of
+	 * all contexts
+	 */
+	DBLIST_REMOVE(&db, ctx);
+
+	/* Disconnect all connections */
+	db_disconnect(ctx);
+
+	/* Destroy the list of all connections */
+	DBLIST_FOREACH_SAFE(con, &ctx->con, tmp_con) {
+ 		DBLIST_REMOVE_HEAD(&ctx->con);
+		db_con_free(con);
+	}
+
+	/* Dispose all driver specific data structures as well as
+	 * the data structures in db_ctx_data linked list
+	 */
+	SLIST_FOREACH_SAFE(ptr, &ctx->data, next, ptr2) {
+		if (ptr->data) ptr->data->free(ptr->data);
+		db_ctx_data_free(ptr);
+	}
+	/* Clear all pointers to attached data structures because we have
+	 * freed the attached data structures above already. This is to
+	 * ensure that the call to db_gen_free below will not try to free
+	 * them one more time
+	 */
+	memset(((db_gen_t*)ctx)->data, '\0', sizeof(((db_gen_t*)ctx)->data));
+	db_gen_free(&ctx->gen);
+	
+	/* Destroy the structure */
+	if (ctx->id.s) pkg_free(ctx->id.s);
+    pkg_free(ctx);
+}
+
+
+/*
+ * This function traverses the linked list of all db_ctx_data
+ * structures stored in a database context to find out whether
+ * db_ctx function of the driver whose name is in "module"
+ * parameter has already been called.
+ */
+static struct db_ctx_data* lookup_ctx_data(db_ctx_t* ctx, str* module)
+{
+	struct db_ctx_data* ptr;
+
+	SLIST_FOREACH(ptr, &ctx->data, next) {
+		if (ptr->module.len == module->len &&
+			!memcmp(ptr->module.s, module->s, module->len)) {
+			return ptr;
+		}
+	}
+	return NULL;
+}
+
+
+/*
+ * Add a new database to database context
+ */
+int db_add_db(db_ctx_t* ctx, const char* uri)
+{
+	db_con_t* con;
+	db_uri_t* parsed_uri = NULL;
+	struct db_ctx_data* d;
+
+	/* Make sure we do not attempt to open more than DB_MAX_CON
+	 * database connections within one context
+	 */
+	if (ctx->con_n == DB_PAYLOAD_MAX) {
+		ERR("db_add_db: Too many database connections in db context\n");
+		return -1;
+	}
+
+	/* Get the name of desired database driver */
+	parsed_uri = db_uri(uri);
+	if (parsed_uri == NULL) goto error;
+
+	d = lookup_ctx_data(ctx, &parsed_uri->scheme);
+	if (d) {
+		/* We have already called db_ctx function of this DB driver
+		 * so reuse the result from the previous run and that's it
+		 */
+		db_payload_idx = ctx->con_n;
+		DB_SET_PAYLOAD(ctx, d->data);
+	} else {
+		/* We haven't run db_ctx of the DB driver yet, so call the
+		 * function, let it create the data if needed and then remember
+		 * the result in a newly created db_ctx_data structure
+		 */
+
+		/* Call db_ctx function if the driver has it */
+		if (db_drv_call(&parsed_uri->scheme, "db_ctx", ctx, ctx->con_n) < 0) {
+			goto error;
+		}
+
+		d = db_ctx_data(&parsed_uri->scheme, DB_GET_PAYLOAD(ctx));
+		if (d == NULL) {
+			/* We failed to create db_ctx_data for this payload so we have
+			 * to dispose it manually here before bailing out.
+			 */
+			((struct db_drv*)DB_GET_PAYLOAD(ctx))->free(DB_GET_PAYLOAD(ctx));
+			goto error;
+		}
+
+		/* Add the newly created db_ctx_data structure to the linked list so
+		 * that next time the result stored in the structure will be reused
+		 * if another database connection from the same driver is added to
+		 * the context
+		 */
+		SLIST_INSERT_HEAD(&ctx->data, d, next);
+	}
+
+	/* We must create the db_con structure after lookup_ctx_data and associated
+	 * code above, this is to ensure that db_con in the DB driver gets called 
+	 * after db_ctx in the same driver. db_con function might rely on the
+	 * previously created context structures
+	 */
+	con = db_con(ctx, parsed_uri);
+	if (con == NULL) goto error;
+
+	DBLIST_INSERT_TAIL(&ctx->con, con);
+	ctx->con_n++;
+
+	return 0;
+
+ error:
+	if (parsed_uri) db_uri_free(parsed_uri);
+	return -1;
+}
+
+
+/*
+ * Attempt to connect all connections in the
+ * context
+ */
+int db_connect(db_ctx_t* ctx)
+{
+	db_con_t* con;
+
+	DBLIST_FOREACH(con, &ctx->con) {
+		if (con->connect && con->connect(con) < 0) return -1;
+	}
+	return 0;
+}
+
+
+/*
+ * Disconnect all database connections in the
+ * context
+ */
+void db_disconnect(db_ctx_t* ctx)
+{
+	db_con_t* con;
+
+	DBLIST_FOREACH(con, &ctx->con) {
+		if (con->disconnect) con->disconnect(con);
+	}
+}

db/db_ctx.h

@@ -0,0 +1,104 @@
+/* 
+ * $Id$ 
+ *
+ * Copyright (C) 2001-2003 FhG FOKUS
+ * Copyright (C) 2006-2007 iptelorg GmbH
+ *
+ * This file is part of ser, a free SIP server.
+ *
+ * ser is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version
+ *
+ * For a license to use the ser software under conditions
+ * other than those described here, or to purchase support for this
+ * software, please contact iptel.org by e-mail at the following addresses:
+ *    [email protected]
+ *
+ * ser is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License 
+ * along with this program; if not, write to the Free Software 
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef _DB_CTX_H
+#define _DB_CTX_H  1
+
+#include "../str.h"
+#include "../list.h"
+#include "db_drv.h"
+#include "db_gen.h"
+#include "db_con.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+struct db_ctx;
+
+/* This structure is stored in a linked list inside db_ctx
+ * and is used to lookup driver-specific data based on module
+ * name. A driver can have multiple connections in a context but
+ * it should have only one structure attached to db_ctx structure
+ * (which will be shared by all the connections of that driver in
+ * db_ctx. 
+ */
+struct db_ctx_data {
+	str module;
+	db_drv_t* data;
+	SLIST_ENTRY(db_ctx_data) next;
+};
+
+
+typedef struct db_ctx {
+	db_gen_t gen;    /* Generic data common for all DB API structures */
+	str id;          /* Text id of the context */
+	int con_n;       /* Number of connections in the context */
+	SLIST_HEAD(, db_ctx_data) data;
+   	DBLIST_HEAD(db_ctx_con) con;  /* The list of all connections within the context */
+} db_ctx_t;
+
+	
+/*
+ * Create a new database context
+ */
+struct db_ctx* db_ctx(const char* id);
+
+
+/* Remove the database context structure
+ * from the linked list and free all memory
+ * used by the structure
+ */
+void db_ctx_free(struct db_ctx* ctx);
+
+
+/*
+ * Add a new database to database context
+ */
+int db_add_db(struct db_ctx* ctx, const char* uri);
+
+
+/*
+ * Attempt to connect all connections in the
+ * context
+ */
+int db_connect(struct db_ctx* ctx);
+
+
+/*
+ * Disconnect all database connections in the
+ * context
+ */
+void db_disconnect(struct db_ctx* ctx);
+
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+#endif /* _DB_CTX_H */