Changeset 4359 for pjproject/trunk/pjlib/include/pj/lock.h

Timestamp:

Feb 21, 2013 11:18:36 AM (11 years ago)

Author:

bennylp

Message:

Fixed #1616: Implementation of Group lock and other foundation in PJLIB for fixing synchronization issues

File:

• pjproject/trunk/pjlib/include/pj/lock.h (modified) (1 diff)

pjproject/trunk/pjlib/include/pj/lock.h

@@ -148 +148 @@
 /** @} */
 
+
+/**
+ * @defgroup PJ_GRP_LOCK Group Lock
+ * @ingroup PJ_LOCK
+ * @{
+ *
+ * Group lock is a synchronization object to manage concurrency among members
+ * within the same logical group. Example of such groups are:
+ *
+ *   - dialog, which has members such as the dialog itself, an invite session,
+ *     and several transactions
+ *   - ICE, which has members such as ICE stream transport, ICE session, STUN
+ *     socket, TURN socket, and down to ioqueue key
+ *
+ * Group lock has three functions:
+ *
+ *   - mutual exclusion: to protect resources from being accessed by more than
+ *     one threads at the same time
+ *   - session management: to make sure that the resource is not destroyed
+ *     while others are still using or about to use it.
+ *   - lock coordinator: to provide uniform lock ordering among more than one
+ *     lock objects, which is necessary to avoid deadlock.
+ *
+ * The requirements of the group lock are:
+ *
+ *    - must satisfy all the functions above
+ *    - must allow members to join or leave the group (for example,
+ *      transaction may be added or removed from a dialog)
+ *    - must be able to synchronize with external lock (for example, a dialog
+ *      lock must be able to sync itself with PJSUA lock)
+ *
+ * Please see https://trac.pjsip.org/repos/wiki/Group_Lock for more info.
+ */
+
+/**
+ * Settings for creating the group lock.
+ */
+typedef struct pj_grp_lock_config
+{
+    /**
+     * Creation flags, currently must be zero.
+     */
+    unsigned    flags;
+
+} pj_grp_lock_config;
+
+
+/**
+ * Initialize the config with the default values.
+ *
+ * @param cfg           The config to be initialized.
+ */
+PJ_DECL(void) pj_grp_lock_config_default(pj_grp_lock_config *cfg);
+
+/**
+ * Create a group lock object. Initially the group lock will have reference
+ * counter of one.
+ *
+ * @param pool          The group lock only uses the pool parameter to get
+ *                      the pool factory, from which it will create its own
+ *                      pool.
+ * @param cfg           Optional configuration.
+ * @param p_grp_lock    Pointer to receive the newly created group lock.
+ *
+ * @return              PJ_SUCCESS or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_grp_lock_create(pj_pool_t *pool,
+                                        const pj_grp_lock_config *cfg,
+                                        pj_grp_lock_t **p_grp_lock);
+
+/**
+ * Forcibly destroy the group lock, ignoring the reference counter value.
+ *
+ * @param grp_lock      The group lock.
+ *
+ * @return              PJ_SUCCESS or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_grp_lock_destroy( pj_grp_lock_t *grp_lock);
+
+/**
+ * Move the contents of the old lock to the new lock and destroy the
+ * old lock.
+ *
+ * @param old_lock      The old group lock to be destroyed.
+ * @param new_lock      The new group lock.
+ *
+ * @return              PJ_SUCCESS or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_grp_lock_replace(pj_grp_lock_t *old_lock,
+                                         pj_grp_lock_t *new_lock);
+
+/**
+ * Acquire lock on the specified group lock.
+ *
+ * @param grp_lock      The group lock.
+ *
+ * @return              PJ_SUCCESS or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_grp_lock_acquire( pj_grp_lock_t *grp_lock);
+
+/**
+ * Acquire lock on the specified group lock if it is available, otherwise
+ * return immediately wihout waiting.
+ *
+ * @param grp_lock      The group lock.
+ *
+ * @return              PJ_SUCCESS or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_grp_lock_tryacquire( pj_grp_lock_t *grp_lock);
+
+/**
+ * Release the previously held lock. This may cause the group lock
+ * to be destroyed if it is the last one to hold the reference counter.
+ * In that case, the function will return PJ_EGONE.
+ *
+ * @param grp_lock      The group lock.
+ *
+ * @return              PJ_SUCCESS or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_grp_lock_release( pj_grp_lock_t *grp_lock);
+
+/**
+ * Add a destructor handler, to be called by the group lock when it is
+ * about to be destroyed.
+ *
+ * @param grp_lock      The group lock.
+ * @param pool          Pool to allocate memory for the handler.
+ * @param member        A pointer to be passed to the handler.
+ * @param handler       The destroy handler.
+ *
+ * @return              PJ_SUCCESS or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_grp_lock_add_handler(pj_grp_lock_t *grp_lock,
+                                             pj_pool_t *pool,
+                                             void *member,
+                                             void (*handler)(void *member));
+
+/**
+ * Remove previously registered handler. All parameters must be the same
+ * as when the handler was added.
+ *
+ * @param grp_lock      The group lock.
+ * @param member        A pointer to be passed to the handler.
+ * @param handler       The destroy handler.
+ *
+ * @return              PJ_SUCCESS or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_grp_lock_del_handler(pj_grp_lock_t *grp_lock,
+                                             void *member,
+                                             void (*handler)(void *member));
+
+/**
+ * Increment reference counter to prevent the group lock grom being destroyed.
+ *
+ * @param grp_lock      The group lock.
+ *
+ * @return              PJ_SUCCESS or the appropriate error code.
+ */
+#if !PJ_GRP_LOCK_DEBUG
+PJ_DECL(pj_status_t) pj_grp_lock_add_ref(pj_grp_lock_t *grp_lock);
+
+#define pj_grp_lock_add_ref_dbg(grp_lock, x, y) pj_grp_lock_add_ref(grp_lock)
+
+#else
+
+#define pj_grp_lock_add_ref(g)  pj_grp_lock_add_ref_dbg(g, __FILE__, __LINE__)
+
+PJ_DECL(pj_status_t) pj_grp_lock_add_ref_dbg(pj_grp_lock_t *grp_lock,
+                                             const char *file,
+                                             int line);
+#endif
+
+/**
+ * Decrement the reference counter. When the counter value reaches zero, the
+ * group lock will be destroyed and all destructor handlers will be called.
+ *
+ * @param grp_lock      The group lock.
+ *
+ * @return              PJ_SUCCESS or the appropriate error code.
+ */
+#if !PJ_GRP_LOCK_DEBUG
+PJ_DECL(pj_status_t) pj_grp_lock_dec_ref(pj_grp_lock_t *grp_lock);
+
+#define pj_grp_lock_dec_ref_dbg(grp_lock, x, y) pj_grp_lock_dec_ref(grp_lock)
+#else
+
+#define pj_grp_lock_dec_ref(g)  pj_grp_lock_dec_ref_dbg(g, __FILE__, __LINE__)
+
+PJ_DECL(pj_status_t) pj_grp_lock_dec_ref_dbg(pj_grp_lock_t *grp_lock,
+                                             const char *file,
+                                             int line);
+
+#endif
+
+/**
+ * Get current reference count value. This normally is only used for
+ * debugging purpose.
+ *
+ * @param grp_lock      The group lock.
+ *
+ * @return              The reference count value.
+ */
+PJ_DECL(int) pj_grp_lock_get_ref(pj_grp_lock_t *grp_lock);
+
+
+/**
+ * Dump group lock info for debugging purpose. If group lock debugging is
+ * enabled (via PJ_GRP_LOCK_DEBUG) macro, this will print the group lock
+ * reference counter value along with the source file and line. If
+ * debugging is disabled, this will only print the reference counter.
+ *
+ * @param grp_lock      The group lock.
+ */
+PJ_DECL(void) pj_grp_lock_dump(pj_grp_lock_t *grp_lock);
+
+
+/**
+ * Synchronize an external lock with the group lock, by adding it to the
+ * list of locks to be acquired by the group lock when the group lock is
+ * acquired.
+ *
+ * The ''pos'' argument specifies the lock order and also the relative
+ * position with regard to lock ordering against the group lock. Locks with
+ * lower ''pos'' value will be locked first, and those with negative value
+ * will be locked before the group lock (the group lock's ''pos'' value is
+ * zero).
+ *
+ * @param grp_lock      The group lock.
+ * @param ext_lock      The external lock
+ * @param pos           The position.
+ *
+ * @return              PJ_SUCCESS or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_grp_lock_chain_lock(pj_grp_lock_t *grp_lock,
+                                            pj_lock_t *ext_lock,
+                                            int pos);
+
+/**
+ * Remove an external lock from group lock's list of synchronized locks.
+ *
+ * @param grp_lock      The group lock.
+ * @param ext_lock      The external lock
+ *
+ * @return              PJ_SUCCESS or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_grp_lock_unchain_lock(pj_grp_lock_t *grp_lock,
+                                              pj_lock_t *ext_lock);
+
+
+/** @} */
+
+
 PJ_END_DECL