Add assert()s to mem2.c (activated by SQLITE_MEMDEBUG) which verify that

memory alloctions that might have come from lookaside are always freed
using a lookaside-aware free routine.

FossilOrigin-Name: c2af2164cf7b279ebb3e08201561348be6e765df

1 files changed, 39 insertions, 0 deletions

diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index a21513d23..c674b71bd 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -3089,4 +3089,43 @@ SQLITE_EXTERN void (*sqlite3IoTrace)(const char*,...);
 # define sqlite3VdbeIOTraceSql(X)
 #endif
 
+/*
+** These routines are available for the mem2.c debugging memory allocator
+** only.  They are used to verify that different "types" of memory
+** allocations are properly tracked by the system.
+**
+** sqlite3MemdebugSetType() sets the "type" of an allocation to one of
+** the MEMTYPE_* macros defined below.  The type must be a bitmask with
+** a single bit set.
+**
+** sqlite3MemdebugHasType() returns true if any of the bits in its second
+** argument match the type set by the previous sqlite3MemdebugSetType().
+** sqlite3MemdebugHasType() is intended for use inside assert() statements.
+** For example:
+**
+**     assert( sqlite3MemdebugHasType(p, MEMTYPE_HEAP) );
+**
+** Perhaps the most important point is the difference between MEMTYPE_HEAP
+** and MEMTYPE_DB.  If an allocation is MEMTYPE_DB, that means it might have
+** been allocated by lookaside, except the allocation was too large or
+** lookaside was already full.  It is important to verify that allocations
+** that might have been satisfied by lookaside are not passed back to 
+** non-lookaside free() routines.  Asserts such as the example above are
+** placed on the non-lookaside free() routines to verify this constraint. 
+**
+** All of this is no-op for a production build.  It only comes into
+** play when the SQLITE_MEMDEBUG compile-time option is used.
+*/
+#ifdef SQLITE_MEMDEBUG
+  void sqlite3MemdebugSetType(void*,u8);
+  int sqlite3MemdebugHasType(void*,u8);
+#else
+# define sqlite3MemdebugSetType(X,Y)  /* no-op */
+# define sqlite3MemdebugHasType(X,Y)  1
 #endif
+#define MEMTYPE_HEAP     0x01    /* General heap allocations */
+#define MEMTYPE_DB       0x02    /* Associated with a database connection */
+#define MEMTYPE_SCRATCH  0x04    /* Scratch allocations */
+#define MEMTYPE_PCACHE   0x08    /* Page cache allocations */
+
+#endif /* _SQLITEINT_H_ */