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res_odbc: Remove connection management 

Asterisk by default will create a single database connection and share
it among all threads that attempt to access the database. In previous
versions of Asterisk, this was tolerable, because the most used channel
driver, chan_sip, mostly accessed the database from a single thread.
With PJSIP, however, many threads may be attempting to perform database
operations, and there is the potential for many more database accesses,
meaning the concurrency is a horrible bottleneck if only one connection
is shared.

Asterisk has a connection pooling facility built into it, but the
implementation has flaws. For one, there is a strict limit on the number
of simultaneous connections that could be made to the database. Anything
beyond the maximum would result in a failed operation. Attempting to
predict what the maximum should be is nearly impossible even for someone
intimately familiar with Asterisk's threading model. In addition, use of
transactions in the dialplan can cause some severe bugs if connection
pooling is enabled.

This commit seeks to fix the concurrency problem by removing all
connection management code from Asterisk and leaving that to the
underlying unixODBC code instead. Now, Asterisk does not share a single
connection, nor does it try to maintain a connection pool. Instead, all
Asterisk ever does is request a connection from unixODBC and allow
unixODBC to either allocate those connections or retrieve them from a
pool.

Doing this has a bit of a ripple effect. For one, since connections are
not long-lived objects, several of the safeguards that previously
existed have been removed. We don't have to worry about trying to use a
connection that has gone stale. In every case, when we request a
connection, it has just been made and we don't need to perform any
sanity checks to be sure it's still active.

Another major player affected by this change is transactions.
Transactions and their respective connections were so tightly coupled
that it was almost pornographic. This code change moves
transaction-related code to its own file separate from the core ODBC
functionality. This way, the core of ODBC does not even have to know
that transactions exist.

In making this large change, I had to look at a lot of code and
understand it. When making this change, I discovered several places
where the behavior is definitely not ideal, but it seemed outside the
scope of this change to be fixing it. Instead, any place where I saw
some sort of room for improvement has had a XXX comment added explaining
what could be altered to improve it.

Change-Id: I37a84def5ea4ddf93868ce8105f39de078297fbf
This commit is contained in:
Mark Michelson 2015-12-23 15:07:05 -06:00
parent 60a15fe436
commit 9714da7aa4
8 changed files with 765 additions and 1095 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
funcs/func_odbc.c
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@ -42,6 +42,7 @@ ASTERISK_REGISTER_FILE()
#include "asterisk/pbx.h"
#include "asterisk/config.h"
#include "asterisk/res_odbc.h"
#include "asterisk/res_odbc_transaction.h"
#include "asterisk/app.h"
#include "asterisk/cli.h"
#include "asterisk/strings.h"

11
include/asterisk/config.h
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@ -495,6 +495,17 @@ int ast_unload_realtime(const char *family);
*
* \note You should use the constant SENTINEL to terminate arguments, in
* order to preserve cross-platform compatibility.
*
* TODO The return value of this function is routinely ignored. Ignoring
* the return value means that it's mostly pointless to be calling this.
* You'll see some warning messages potentially, but that's it.
*
* XXX This function is super useful for detecting configuration problems
* early, but unfortunately, the latest in configuration management, sorcery,
* doesn't work well with this. Users of sorcery are familiar with the fields
* they will need to write but don't know if realtime is being used. Sorcery
* knows what storage mechanism is being used but has no high-level knowledge
* of what sort of data is going to be written.
*/
int ast_realtime_require_field(const char *family, ...) attribute_sentinel;

78
include/asterisk/res_odbc.h
View File

@ -46,16 +46,11 @@ enum {
struct odbc_obj {
SQLHDBC con; /*!< ODBC Connection Handle */
struct odbc_class *parent; /*!< Information about the connection is protected */
struct timeval last_used; /*!< Used by idlecheck to determine if the connection should be renegotiated */
#ifdef DEBUG_THREADS
char file[80];
char function[80];
int lineno;
#endif
unsigned int used:1; /*!< Is this connection currently in use? */
unsigned int up:1;
unsigned int tx:1; /*!< Should this connection be unshared, regardless of the class setting? */
struct odbc_txn_frame *txf; /*!< Reference back to the transaction frame, if applicable */
AST_LIST_ENTRY(odbc_obj) list;
};
@ -102,39 +97,29 @@ int ast_odbc_smart_execute(struct odbc_obj *obj, SQLHSTMT stmt) __attribute__((d
/*!
* \brief Retrieves a connected ODBC object
* \param name The name of the ODBC class for which a connection is needed.
* \param flags One or more of the following flags:
* \li RES_ODBC_SANITY_CHECK Whether to ensure that a connection is valid before returning the handle. Usually unnecessary.
* \li RES_ODBC_INDEPENDENT_CONNECTION Return a handle which is independent from all others. Usually used when starting a transaction.
* \li RES_ODBC_CONNECTED Only return a connected handle. Intended for use with peers which use idlecheck, which are checked periodically for reachability.
* \param file, function, lineno
*
* \return ODBC object
* \retval NULL if there is no connection available with the requested name.
* \deprecated
*
* Connection classes may, in fact, contain multiple connection handles. If
* the connection is pooled, then each connection will be dedicated to the
* thread which requests it. Note that all connections should be released
* when the thread is done by calling ast_odbc_release_obj(), below.
* This is only around for backwards-compatibility with older versions of Asterisk.
*/
struct odbc_obj *_ast_odbc_request_obj2(const char *name, struct ast_flags flags, const char *file, const char *function, int lineno);
/*!
* \brief Get a ODBC connection object
*
* The "check" parameter is leftover from an earlier implementation where database connections
* were cached by res_odbc. Since connections are managed by unixODBC now, this parameter is
* only kept around for API compatibility.
*
* \param name The name of the res_odbc.conf section describing the database to connect to
* \param check unused
* \return A connection to the database. Call ast_odbc_release_obj() when finished.
*/
struct odbc_obj *_ast_odbc_request_obj(const char *name, int check, const char *file, const char *function, int lineno);
#define ast_odbc_request_obj2(a, b) _ast_odbc_request_obj2(a, b, __FILE__, __PRETTY_FUNCTION__, __LINE__)
#define ast_odbc_request_obj(a, b) _ast_odbc_request_obj(a, b, __FILE__, __PRETTY_FUNCTION__, __LINE__)
/*!
* \brief Retrieve a stored ODBC object, if a transaction has been started.
* \param chan Channel associated with the transaction.
* \param objname Name of the database handle. This name corresponds to the name passed
* to \see ast_odbc_request_obj2 (or formerly, to ast_odbc_request_obj). Note that the
* existence of this parameter name explicitly allows for multiple transactions to be open
* at once, albeit to different databases.
* \retval A stored ODBC object, if a transaction was already started.
* \retval NULL, if no transaction yet exists.
*/
struct odbc_obj *ast_odbc_retrieve_transaction_obj(struct ast_channel *chan, const char *objname);
/*!
* \brief Releases an ODBC object previously allocated by ast_odbc_request_obj()
* \param obj The ODBC object
@ -223,4 +208,39 @@ int ast_odbc_clear_cache(const char *database, const char *tablename);
*/
SQLRETURN ast_odbc_ast_str_SQLGetData(struct ast_str **buf, int pmaxlen, SQLHSTMT StatementHandle, SQLUSMALLINT ColumnNumber, SQLSMALLINT TargetType, SQLLEN *StrLen_or_Ind);
/*!
* \brief Shortcut for printing errors to logs after a failed SQL operation.
*
* \param handle_type The type of SQL handle on which to gather diagnostics
* \param handle The SQL handle to gather diagnostics from
* \param operation The name of the failed operation.
* \return The error string that was printed to the logs
*/
struct ast_str *ast_odbc_print_errors(SQLSMALLINT handle_type, SQLHANDLE handle, const char *operation);
/*!
* \brief Get the transaction isolation setting for an ODBC class
*/
unsigned int ast_odbc_class_get_isolation(struct odbc_class *class);
/*!
* \brief Get the transaction forcecommit setting for an ODBC class
*/
unsigned int ast_odbc_class_get_forcecommit(struct odbc_class *class);
/*!
* \brief Get the name of an ODBC class.
*/
const char *ast_odbc_class_get_name(struct odbc_class *class);
/*!
* \brief Convert from textual transaction isolation values to their numeric constants
*/
int ast_odbc_text2isolation(const char *txt);
/*!
* \brief Convert from numeric transaction isolation values to their textual counterparts
*/
const char *ast_odbc_isolation2text(int iso);
#endif /* _ASTERISK_RES_ODBC_H */

54
include/asterisk/res_odbc_transaction.h Normal file
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@ -0,0 +1,54 @@
/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 2016, Digium, Inc.
*
* Mark Michelson <mmichelson@digium.com>
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2. See the LICENSE file
* at the top of the source tree.
*/
#ifndef RES_ODBC_TRANSACTION_H
#define RES_ODBC_TRANSACTION_H
/*!
* \brief
*
* Retrieve an ODBC transaction connection with the given ODBC class name.
*
* \note The name passed here is *not* the name of the transaction but the name of the
* ODBC class defined in res_odbc.conf.
*
* \note Do not call ast_odbc_release_obj() on the retrieved connection. Calling this function
* does not make you the owner of the connection.
*
* XXX This function is majorly flawed because it ignores properties of transactions and simply
* finds one that corresponds to the given DSN. The problem here is that transactions have names
* and they maintain which transaction is "active" for operations like transaction creation,
* commit, and rollback. However, when it comes to intermediary operations to be made on the
* transactions, all that is ignored. It means that if a channel has created multiple transactions
* for the same DSN, it's a crapshoot which of those transactions the operation will be performed
* on. This can potentially lead to baffling errors under the right circumstances.
*
* XXX The semantics of this function make for writing some awkward code. If you use func_odbc as
* an example, it has to first try to retrieve a transactional connection, then failing that, create
* a non-transactional connection. The result is that it has to remember which type of connection it's
* using and know whether to release the connection when completed or not. It would be much better
* if callers did not have to jump through such hoops.
*
* \param chan Channel on which the ODBC transaction was created
* \param objname The name of the ODBC class configured in res_odbc.conf
* \retval NULL Transaction connection could not be found.
* \retval non-NULL A transactional connection
*/
struct odbc_obj *ast_odbc_retrieve_transaction_obj(struct ast_channel *chan, const char *objname);
#endif /* RES_ODBC_TRANSACTION_H */

1175
res/res_odbc.c
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File diff suppressed because it is too large Load Diff

6
res/res_odbc.exports.in
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@ -12,9 +12,13 @@
LINKER_SYMBOL_PREFIX_ast_odbc_request_obj;
LINKER_SYMBOL_PREFIXast_odbc_request_obj2;
LINKER_SYMBOL_PREFIX_ast_odbc_request_obj2;
LINKER_SYMBOL_PREFIXast_odbc_retrieve_transaction_obj;
LINKER_SYMBOL_PREFIXast_odbc_sanity_check;
LINKER_SYMBOL_PREFIXast_odbc_smart_execute;
LINKER_SYMBOL_PREFIXast_odbc_class_get_isolation;
LINKER_SYMBOL_PREFIXast_odbc_class_get_forcecommit;
LINKER_SYMBOL_PREFIXast_odbc_class_get_name;
LINKER_SYMBOL_PREFIXast_odbc_text2isolation;
LINKER_SYMBOL_PREFIXast_odbc_isolation2text;
local:
*;
};

529
res/res_odbc_transaction.c Normal file
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@ -0,0 +1,529 @@
/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 2016, Digium, Inc.
*
* Mark Michelson <mmichelson@digium.com>
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2. See the LICENSE file
* at the top of the source tree.
*/
#include "asterisk.h"
#include "asterisk/res_odbc.h"
#include "asterisk/res_odbc_transaction.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/app.h"
#include "asterisk/module.h"
/*** MODULEINFO
<depend>res_odbc</depend>
<support_level>core</support_level>
***/
/*** DOCUMENTATION
<function name="ODBC" language="en_US">
<synopsis>
Controls ODBC transaction properties.
</synopsis>
<syntax>
<parameter name="property" required="true">
<enumlist>
<enum name="transaction">
<para>Gets or sets the active transaction ID. If set, and the transaction ID does not
exist and a <replaceable>database name</replaceable> is specified as an argument, it will be created.</para>
</enum>
<enum name="forcecommit">
<para>Controls whether a transaction will be automatically committed when the channel
hangs up. Defaults to false. If a <replaceable>transaction ID</replaceable> is specified in the optional argument,
the property will be applied to that ID, otherwise to the current active ID.</para>
</enum>
<enum name="isolation">
<para>Controls the data isolation on uncommitted transactions. May be one of the
following: <literal>read_committed</literal>, <literal>read_uncommitted</literal>,
<literal>repeatable_read</literal>, or <literal>serializable</literal>. Defaults to the
database setting in <filename>res_odbc.conf</filename> or <literal>read_committed</literal>
if not specified. If a <replaceable>transaction ID</replaceable> is specified as an optional argument, it will be
applied to that ID, otherwise the current active ID.</para>
</enum>
</enumlist>
</parameter>
<parameter name="argument" required="false" />
</syntax>
<description>
<para>The ODBC() function allows setting several properties to influence how a connected
database processes transactions.</para>
</description>
</function>
<application name="ODBC_Commit" language="en_US">
<synopsis>
Commits a currently open database transaction.
</synopsis>
<syntax>
<parameter name="transaction ID" required="no" />
</syntax>
<description>
<para>Commits the database transaction specified by <replaceable>transaction ID</replaceable>
or the current active transaction, if not specified.</para>
</description>
</application>
<application name="ODBC_Rollback" language="en_US">
<synopsis>
Rollback a currently open database transaction.
</synopsis>
<syntax>
<parameter name="transaction ID" required="no" />
</syntax>
<description>
<para>Rolls back the database transaction specified by <replaceable>transaction ID</replaceable>
or the current active transaction, if not specified.</para>
</description>
</application>
***/
struct odbc_txn_frame {
AST_LIST_ENTRY(odbc_txn_frame) list;
struct odbc_obj *obj; /*!< Database handle within which transacted statements are run */
/*!\brief Is this record the current active transaction within the channel?
* Note that the active flag is really only necessary for statements which
* are triggered from the dialplan, as there isn't a direct correlation
* between multiple statements. Applications wishing to use transactions
* may simply perform each statement on the same odbc_obj, which keeps the
* transaction persistent.
*/
unsigned int active:1;
unsigned int forcecommit:1; /*!< Should uncommitted transactions be auto-committed on handle release? */
unsigned int isolation; /*!< Flags for how the DB should deal with data in other, uncommitted transactions */
char name[0]; /*!< Name of this transaction ID */
};
static struct odbc_txn_frame *release_transaction(struct odbc_txn_frame *tx);
static void odbc_txn_free(void *vdata)
{
struct odbc_txn_frame *tx;
AST_LIST_HEAD(, odbc_txn_frame) *oldlist = vdata;
ast_debug(2, "odbc_txn_free(%p) called\n", vdata);
AST_LIST_LOCK(oldlist);
while ((tx = AST_LIST_REMOVE_HEAD(oldlist, list))) {
release_transaction(tx);
}
AST_LIST_UNLOCK(oldlist);
AST_LIST_HEAD_DESTROY(oldlist);
ast_free(oldlist);
}
static const struct ast_datastore_info txn_info = {
.type = "ODBC_Transaction",
.destroy = odbc_txn_free,
};
static struct odbc_txn_frame *create_transaction(struct ast_channel *chan, const char *name, const char *dsn)
{
struct ast_datastore *txn_store;
AST_LIST_HEAD(, odbc_txn_frame) *oldlist;
struct odbc_txn_frame *txn = NULL;
struct odbc_txn_frame *otxn;
if (ast_strlen_zero(dsn)) {
return NULL;
}
ast_channel_lock(chan);
if ((txn_store = ast_channel_datastore_find(chan, &txn_info, NULL))) {
oldlist = txn_store->data;
} else {
if (!(txn_store = ast_datastore_alloc(&txn_info, NULL))) {
ast_log(LOG_ERROR, "Unable to allocate a new datastore. Cannot create a new transaction.\n");
ast_channel_unlock(chan);
return NULL;
}
if (!(oldlist = ast_calloc(1, sizeof(*oldlist)))) {
ast_log(LOG_ERROR, "Unable to allocate datastore list head. Cannot create a new transaction.\n");
ast_datastore_free(txn_store);
ast_channel_unlock(chan);
return NULL;
}
txn_store->data = oldlist;
AST_LIST_HEAD_INIT(oldlist);
ast_channel_datastore_add(chan, txn_store);
}
ast_channel_unlock(chan);
txn = ast_calloc(1, sizeof(*txn) + strlen(name) + 1);
if (!txn) {
return NULL;
}
strcpy(txn->name, name); /* SAFE */
txn->obj = ast_odbc_request_obj(dsn, 0);
if (!txn->obj) {
ast_free(txn);
return NULL;
}
txn->isolation = ast_odbc_class_get_isolation(txn->obj->parent);
txn->forcecommit = ast_odbc_class_get_isolation(txn->obj->parent);
txn->active = 1;
if (SQLSetConnectAttr(txn->obj->con, SQL_ATTR_AUTOCOMMIT, (void *)SQL_AUTOCOMMIT_OFF, 0) == SQL_ERROR) {
ast_odbc_print_errors(SQL_HANDLE_DBC, txn->obj->con, "SetConnectAttr (Autocommit)");
ast_odbc_release_obj(txn->obj);
ast_free(txn);
return NULL;
}
/* Set the isolation property */
if (SQLSetConnectAttr(txn->obj->con, SQL_ATTR_TXN_ISOLATION, (void *)(long)txn->isolation, 0) == SQL_ERROR) {
ast_odbc_print_errors(SQL_HANDLE_DBC, txn->obj->con, "SetConnectAttr");
ast_odbc_release_obj(txn->obj);
ast_free(txn);
return NULL;
}
/* On creation, the txn becomes active, and all others inactive */
AST_LIST_LOCK(oldlist);
AST_LIST_TRAVERSE(oldlist, otxn, list) {
otxn->active = 0;
}
AST_LIST_INSERT_TAIL(oldlist, txn, list);
AST_LIST_UNLOCK(oldlist);
return txn;
}
static struct odbc_txn_frame *find_transaction(struct ast_channel *chan, const char *name, int active)
{
struct ast_datastore *txn_store;
AST_LIST_HEAD(, odbc_txn_frame) *oldlist;
struct odbc_txn_frame *txn = NULL;
if (!chan || (!active && !name)) {
return NULL;
}
ast_channel_lock(chan);
txn_store = ast_channel_datastore_find(chan, &txn_info, NULL);
ast_channel_unlock(chan);
if (!txn_store) {
/* No datastore? Definitely no transaction then */
return NULL;
}
oldlist = txn_store->data;
AST_LIST_LOCK(oldlist);
AST_LIST_TRAVERSE(oldlist, txn, list) {
if (active) {
if (txn->active) {
break;
}
} else if (!strcasecmp(txn->name, name)) {
break;
}
}
AST_LIST_UNLOCK(oldlist);
return txn;
}
static struct odbc_txn_frame *release_transaction(struct odbc_txn_frame *tx)
{
if (!tx) {
return NULL;
}
ast_debug(2, "release_transaction(%p) called (tx->obj = %p\n", tx, tx->obj);
ast_debug(1, "called on a transactional handle with %s\n", tx->forcecommit ? "COMMIT" : "ROLLBACK");
if (SQLEndTran(SQL_HANDLE_DBC, tx->obj->con, tx->forcecommit ? SQL_COMMIT : SQL_ROLLBACK) == SQL_ERROR) {
ast_odbc_print_errors(SQL_HANDLE_DBC, tx->obj->con, "SQLEndTran");
}
/* Transaction is done, reset autocommit
*
* XXX I'm unsure if this is actually necessary, since we're releasing
* the connection back to unixODBC. However, if unixODBC pooling is enabled,
* it can't hurt to do just in case.
*/
if (SQLSetConnectAttr(tx->obj->con, SQL_ATTR_AUTOCOMMIT, (void *)SQL_AUTOCOMMIT_ON, 0) == SQL_ERROR) {
ast_odbc_print_errors(SQL_HANDLE_DBC, tx->obj->con, "SQLSetAttr");
}
ast_odbc_release_obj(tx->obj);
ast_free(tx);
return NULL;
}
static int commit_exec(struct ast_channel *chan, const char *data)
{
struct odbc_txn_frame *tx;
if (ast_strlen_zero(data)) {
tx = find_transaction(chan, NULL, 1);
} else {
tx = find_transaction(chan, data, 0);
}
/* XXX COMMIT_RESULT is set to OK even if no transaction was found. Very misleading */
pbx_builtin_setvar_helper(chan, "COMMIT_RESULT", "OK");
if (tx) {
if (SQLEndTran(SQL_HANDLE_DBC, tx->obj->con, SQL_COMMIT) == SQL_ERROR) {
struct ast_str *errors = ast_odbc_print_errors(SQL_HANDLE_DBC, tx->obj->con, "SQLEndTran");
pbx_builtin_setvar_helper(chan, "COMMIT_RESULT", ast_str_buffer(errors));
}
}
return 0;
}
static int rollback_exec(struct ast_channel *chan, const char *data)
{
struct odbc_txn_frame *tx;
if (ast_strlen_zero(data)) {
tx = find_transaction(chan, NULL, 1);
} else {
tx = find_transaction(chan, data, 0);
}
/* XXX ROLLBACK_RESULT is set to OK even if no transaction was found. Very misleading */
pbx_builtin_setvar_helper(chan, "ROLLBACK_RESULT", "OK");
if (tx) {
if (SQLEndTran(SQL_HANDLE_DBC, tx->obj->con, SQL_ROLLBACK) == SQL_ERROR) {
struct ast_str *errors = ast_odbc_print_errors(SQL_HANDLE_DBC, tx->obj->con, "SQLEndTran");
pbx_builtin_setvar_helper(chan, "ROLLBACK_RESULT", ast_str_buffer(errors));
}
}
return 0;
}
static int acf_transaction_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
{
AST_DECLARE_APP_ARGS(args,
AST_APP_ARG(property);
AST_APP_ARG(opt);
);
struct odbc_txn_frame *tx;
AST_STANDARD_APP_ARGS(args, data);
if (strcasecmp(args.property, "transaction") == 0) {
if ((tx = find_transaction(chan, NULL, 1))) {
ast_copy_string(buf, tx->name, len);
return 0;
}
} else if (strcasecmp(args.property, "isolation") == 0) {
if (!ast_strlen_zero(args.opt)) {
tx = find_transaction(chan, args.opt, 0);
} else {
tx = find_transaction(chan, NULL, 1);
}
if (tx) {
ast_copy_string(buf, ast_odbc_isolation2text(tx->isolation), len);
return 0;
}
} else if (strcasecmp(args.property, "forcecommit") == 0) {
if (!ast_strlen_zero(args.opt)) {
tx = find_transaction(chan, args.opt, 0);
} else {
tx = find_transaction(chan, NULL, 1);
}
if (tx) {
ast_copy_string(buf, tx->forcecommit ? "1" : "0", len);
return 0;
}
}
return -1;
}
/* XXX The idea of "active" transactions is silly and makes things
* more prone to error. It would be much better if the transaction
* always had to be specified by name so that no implicit behavior
* occurred.
*/
static int mark_transaction_active(struct ast_channel *chan, struct odbc_txn_frame *tx)
{
struct ast_datastore *txn_store;
AST_LIST_HEAD(, odbc_txn_frame) *oldlist;
struct odbc_txn_frame *active = NULL, *txn;
if (!chan) {
return -1;
}
ast_channel_lock(chan);
if (!(txn_store = ast_channel_datastore_find(chan, &txn_info, NULL))) {
ast_channel_unlock(chan);
return -1;
}
oldlist = txn_store->data;
AST_LIST_LOCK(oldlist);
AST_LIST_TRAVERSE(oldlist, txn, list) {
if (txn == tx) {
txn->active = 1;
active = txn;
} else {
txn->active = 0;
}
}
AST_LIST_UNLOCK(oldlist);
ast_channel_unlock(chan);
return active ? 0 : -1;
}
static int acf_transaction_write(struct ast_channel *chan, const char *cmd, char *s, const char *value)
{
AST_DECLARE_APP_ARGS(args,
AST_APP_ARG(property);
AST_APP_ARG(opt);
);
struct odbc_txn_frame *tx;
AST_STANDARD_APP_ARGS(args, s);
if (strcasecmp(args.property, "transaction") == 0) {
/* Set active transaction */
if ((tx = find_transaction(chan, value, 0))) {
mark_transaction_active(chan, tx);
} else if (!create_transaction(chan, value, args.opt)) {
pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "FAILED_TO_CREATE");
return -1;
}
pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "OK");
return 0;
} else if (strcasecmp(args.property, "forcecommit") == 0) {
/* Set what happens when an uncommitted transaction ends without explicit Commit or Rollback */
if (ast_strlen_zero(args.opt)) {
tx = find_transaction(chan, NULL, 1);
} else {
tx = find_transaction(chan, args.opt, 0);
}
if (!tx) {
pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "FAILED_TO_CREATE");
return -1;
}
if (ast_true(value)) {
tx->forcecommit = 1;
} else if (ast_false(value)) {
tx->forcecommit = 0;
} else {
ast_log(LOG_ERROR, "Invalid value for forcecommit: '%s'\n", S_OR(value, ""));
pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "INVALID_VALUE");
return -1;
}
pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "OK");
return 0;
} else if (strcasecmp(args.property, "isolation") == 0) {
/* How do uncommitted transactions affect reads? */
/* XXX This is completely useless. The problem is that setting the isolation here
* does not actually alter the connection. The only time the isolation gets set is
* when the transaction is created. The only way to set isolation is to set it on
* the ODBC class's configuration in res_odbc.conf.
*/
int isolation = ast_odbc_text2isolation(value);
if (ast_strlen_zero(args.opt)) {
tx = find_transaction(chan, NULL, 1);
} else {
tx = find_transaction(chan, args.opt, 0);
}
if (!tx) {
pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "FAILED_TO_CREATE");
return -1;
}
if (isolation == 0) {
pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "INVALID_VALUE");
ast_log(LOG_ERROR, "Invalid isolation specification: '%s'\n", S_OR(value, ""));
} else if (SQLSetConnectAttr(tx->obj->con, SQL_ATTR_TXN_ISOLATION, (void *)(long)isolation, 0) == SQL_ERROR) {
pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "SQL_ERROR");
ast_odbc_print_errors(SQL_HANDLE_DBC, tx->obj->con, "SetConnectAttr (Txn isolation)");
} else {
pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "OK");
tx->isolation = isolation;
}
return 0;
} else {
ast_log(LOG_ERROR, "Unknown property: '%s'\n", args.property);
return -1;
}
}
struct odbc_obj *ast_odbc_retrieve_transaction_obj(struct ast_channel *chan, const char *objname)
{
struct ast_datastore *txn_store;
AST_LIST_HEAD(, odbc_txn_frame) *oldlist;
struct odbc_txn_frame *txn = NULL;
if (!chan || !objname) {
/* No channel == no transaction */
return NULL;
}
ast_channel_lock(chan);
if ((txn_store = ast_channel_datastore_find(chan, &txn_info, NULL))) {
oldlist = txn_store->data;
} else {
ast_channel_unlock(chan);
return NULL;
}
AST_LIST_LOCK(oldlist);
ast_channel_unlock(chan);
AST_LIST_TRAVERSE(oldlist, txn, list) {
if (txn->obj && txn->obj->parent && !strcmp(ast_odbc_class_get_name(txn->obj->parent), objname)) {
AST_LIST_UNLOCK(oldlist);
return txn->obj;
}
}
AST_LIST_UNLOCK(oldlist);
return NULL;
}
static struct ast_custom_function odbc_function = {
.name = "ODBC",
.read = acf_transaction_read,
.write = acf_transaction_write,
};
static const char * const app_commit = "ODBC_Commit";
static const char * const app_rollback = "ODBC_Rollback";
/* XXX res_odbc takes the path of disallowing unloads from happening.
* It's not a great precedent, but since trying to deal with unloading the module
* while transactions are active seems like a huge pain to deal with, we'll go
* the same way here.
*/
static int unload_module(void)
{
return -1;
}
static int load_module(void)
{
ast_register_application_xml(app_commit, commit_exec);
ast_register_application_xml(app_rollback, rollback_exec);
ast_custom_function_register(&odbc_function);
return 0;
}
AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS | AST_MODFLAG_LOAD_ORDER, "ODBC transaction resource",
.support_level = AST_MODULE_SUPPORT_CORE,
.load = load_module,
.unload = unload_module,
.load_pri = AST_MODPRI_REALTIME_DEPEND,
);

6
res/res_odbc_transaction.exports.in Normal file
View File

@ -0,0 +1,6 @@
{
global:
LINKER_SYMBOL_PREFIXast_odbc_retrieve_transaction_obj;
local:
*;
};