X-Git-Url: http://mj.ucw.cz/gitweb/?a=blobdiff_plain;ds=sidebyside;f=ucw%2Ftrans.h;h=e5e328482f1fc8d165fd2410c3c7138f3bbea2d6;hb=ae2b00416589dfe798fc40f0575f62a0c664798f;hp=665020370ddb27f6f3eacaa3d9c350d6fffaa27b;hpb=847bb5125836ac3c89a9118be60cb077090f4756;p=libucw.git

diff --git a/ucw/trans.h b/ucw/trans.h
index 66502037..e5e32848 100644
--- a/ucw/trans.h
+++ b/ucw/trans.h
@@ -1,7 +1,7 @@
 /*
  *	The UCW Library -- Transactions
  *
- *	(c) 2008 Martin Mares <mj@ucw.cz>
+ *	(c) 2008--2011 Martin Mares <mj@ucw.cz>
  *
  *	This software may be freely distributed and used according to the terms
  *	of the GNU Lesser General Public License.
@@ -10,28 +10,73 @@
 #ifndef _UCW_TRANS_H
 #define _UCW_TRANS_H
 
-#include "ucw/mempool.h"
+#include <ucw/mempool.h>
 
 #include <setjmp.h>
 
-/* Transactions */
-
+/** A structure describing a transaction. All fields are for internal use only. **/
 struct trans {
-  struct trans *prev;
-  struct mempool_state trans_pool_state;
-  struct respool *res_pool;
+  struct trans *prev_trans;
+  struct mempool_state *trans_pool_state;
+  struct respool *rpool;
+  struct respool *prev_rpool;
+  struct exception *thrown_exc;
   jmp_buf jmp;
 };
 
-void trans_init(void);		// Called automatically on trans_open() if needed
-void trans_cleanup(void);	// Free memory occupied by the transaction system pools
+void trans_init(void);		/** Initializes the transaction system for the current thread. Called automatically as needed. **/
+void trans_cleanup(void);	/** Frees memory occupied by the transaction system pools for the current thread. **/
+
+struct trans *trans_open(void);	/** Creates a new transaction. Used inside `TRANS_TRY`. **/
+struct trans *trans_get_current(void);	/** Get a pointer to the currently running transaction, or NULL if there is none. **/
+void trans_commit(void);	/** Commits the current transaction. **/
+void trans_rollback(void);	/** Rolls back the current transaction. **/
+void trans_fold(void);		/** Folds the current transaction to its parent. **/
+void trans_dump(void);		/** Prints out a debugging dump of the transaction stack to stdout. **/
+
+struct mempool *trans_get_pool(void);
+
+/**
+ * Data associated with an exception. Usually, this structure is created
+ * by calling @trans_throw(), but if you want to pass more data, you can
+ * create your own exception and throw it using @trans_throw_exc().
+ **/
+struct exception {
+  const char *id;		// Hierarchical identifier of the exception
+  const char *msg;		// Error message to present to the user
+  void *object;			// Object on which the exception happened
+  // More data specific for the particular `id' can follow
+};
+
+/** Creates an exception and throws it. The error message can contain `printf`-like formatting. **/
+void trans_throw(const char *id, void *object, const char *fmt, ...) FORMAT_CHECK(printf,3,4) NONRET;
+
+/** A `va_list` variant of @trans_throw(). **/
+void trans_vthrow(const char *id, void *object, const char *fmt, va_list args) NONRET;
+
+/** Throw an already constructed exception (or re-throw an exception you have caught). **/
+void trans_throw_exc(struct exception *x) NONRET;
+
+/** Declare the current exception caught and roll back the current transaction. Called from `TRANS_END`. **/
+void trans_caught(void);
+
+struct exception *trans_current_exc(void);	/** Return the exception in flight, or NULL if there is none. **/
+
+#define TRANS_TRY do {				\
+  struct trans *_t = trans_open();		\
+  if (!setjmp(_t->jmp))				\
+    {
 
-struct trans *trans_open(void);
-struct trans *trans_get_current(void);
-void trans_commit(void);
-void trans_rollback(void);
-void trans_dump(void);
+#define TRANS_CATCH(x)				\
+      trans_commit();				\
+    }						\
+  else						\
+    {						\
+      struct exception *x UNUSED = trans_current_exc();
 
-/* Exceptions */
+#define TRANS_END				\
+      trans_caught();				\
+    }						\
+  } while(0)
 
 #endif