TD-153: add defer support

src/util/inc/exception.h

 /*
- * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ * Copyright (c) 2020 TAOS Data, Inc. <jhtao@taosdata.com>
  *
  * This program is free software: you can use, redistribute, and/or modify
  * it under the terms of the GNU Affero General Public License, version 3
@@ -17,33 +17,81 @@
 #define TDENGINE_EXCEPTION_H
 
 #include <setjmp.h>
+#include <stdint.h>
+#include <assert.h>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+/*
+ * exception handling
+ */
 typedef struct SExceptionNode {
    struct SExceptionNode* prev;
    jmp_buf jb;
    int code;
 } SExceptionNode;
 
-void expPushNode( SExceptionNode* node );
-int expPopNode();
-void expThrow( int code );
+void exceptionPushNode( SExceptionNode* node );
+int exceptionPopNode();
+void exceptionThrow( int code );
+
+#define THROW( x )          exceptionThrow( (x) )
+#define CAUGHT_EXCEPTION()  (caught_exception == 1)
 
 #define TRY do { \
     SExceptionNode expNode = { 0 }; \
-    expPushNode( &expNode ); \
-    if( setjmp(expNode.jb) == 0 ) {
+    exceptionPushNode( &expNode ); \
+    int caught_exception = setjmp(expNode.jb); \
+    if( caught_exception == 0 )
+
+#define CATCH( code ) int code = exceptionPopNode(); \
+    if( caught_exception == 1 )
+
+#define FINALLY( code ) int code = exceptionPopNode();
+
+#define END_TRY } while( 0 );
+
+
+/*
+ * defered operations
+ */
+typedef struct SDeferedOperation {
+    void (*wrapper)( struct SDeferedOperation* dp );
+    void* func;
+    void* arg;
+} SDeferedOperation;
+
+void deferExecute( SDeferedOperation* operations, unsigned int numOfOperations );
+void deferWrapper_void_void( SDeferedOperation* dp );
+void deferWrapper_void_ptr( SDeferedOperation* dp );
+void deferWrapper_int_int( SDeferedOperation* dp );
+
+#define DEFER_INIT( MaxOperations ) unsigned int maxDeferedOperations = MaxOperations, numOfDeferedOperations = 0; \
+    SDeferedOperation deferedOperations[MaxOperations]
+
+#define DEFER_PUSH( wrapperFunc, deferedFunc, argument ) do { \
+    assert( numOfDeferedOperations < maxDeferedOperations ); \
+    SDeferedOperation* dp = deferedOperations + numOfDeferedOperations++; \
+    dp->wrapper = wrapperFunc; \
+    dp->func = (void*)deferedFunc; \
+    dp->arg = (void*)argument; \
+} while( 0 )
+
+#define DEFER_POP() do { --numOfDeferedOperations; } while( 0 )
 
-#define CATCH( code ) expPopNode(); \
-    } else { \
-        int code = expPopNode();
+#define DEFER_EXECUTE() do{ \
+    deferExecute( deferedOperations, numOfDeferedOperations ); \
+    numOfDeferedOperations = 0; \
+} while( 0 )
 
-#define END_CATCH } } while( 0 );
+#define DEFER_PUSH_VOID_PTR( func, arg ) DEFER_PUSH( deferWrapper_void_ptr, func, arg )
+#define DEFER_PUSH_INT_INT( func, arg ) DEFER_PUSH( deferWrapper_int_int, func, arg )
+#define DEFER_PUSH_VOID_VOID( func ) DEFER_PUSH( deferWrapper_void_void, func, 0 )
 
-#define THROW( x )   expThrow( (x) )
+#define DEFER_PUSH_FREE( arg ) DEFER_PUSH( deferWrapper_void_ptr, free, arg )
+#define DEFER_PUSH_CLOSE( arg ) DEFER_PUSH( deferWrapper_int_int, close, arg )
 
 #ifdef __cplusplus
 }

src/util/src/exception.c

@@ -3,18 +3,41 @@
 
 static _Thread_local SExceptionNode* expList;
 
-void expPushNode( SExceptionNode* node ) {
+void exceptionPushNode( SExceptionNode* node ) {
     node->prev = expList;
     expList = node;
 }
 
-int expPopNode() {
+int exceptionPopNode() {
     SExceptionNode* node = expList;
     expList = node->prev;
     return node->code;
 }
 
-void expThrow( int code ) {
+void exceptionThrow( int code ) {
     expList->code = code;
     longjmp( expList->jb, 1 );
 }
+
+void deferWrapper_void_ptr( SDeferedOperation* dp ) {
+    void (*func)( void* ) = dp->func;
+    func( dp->arg );
+}
+
+void deferWrapper_int_int( SDeferedOperation* dp ) {
+    int (*func)( int ) = dp->func;
+    func( (int)(intptr_t)(dp->arg) );
+}
+
+void deferWrapper_void_void( SDeferedOperation* dp ) {
+    void (*func)() = dp->func;
+    func();
+}
+
+void deferExecute( SDeferedOperation* operations, unsigned int numOfOperations ) {
+    while( numOfOperations > 0 ) {
+        --numOfOperations;
+        SDeferedOperation* dp = operations + numOfOperations;
+        dp->wrapper( dp );
+    }
+}