On Jul 23, 2009, at 11:16 PM, Zachary Turner wrote: > I was looking into overriding the sqlite_mem_methods interface to > specify my own allocator. The two functions I have a question about > are these: > > int (*xSize)(void*) > int (*xRoundup)(int size); > > I've briefly looked over the source code it *seems* like I can safely > return 0 from xSize and 'size' from xRoundup, with the only effects > being that functions such as sqlite_mem_used() will be useless. Are > there any more subtle implications of implementing these functions in > the aforementioned way that I'm missing?
Yes. Returning a copy of the 'size' parameter from xRoundup() will work, but there are at least a few places in the code that depend on a working sqlite3DbMallocSize(). Which sometimes needs to call xSize(). > the problem is that I have a 3rd party allocator that is extremely > fast and implements malloc, free, and realloc, but does not implement > the other functions. I can probably implement xRoundup if necessary > by figuring out their allocation / alignment algorithm and > re-implementing the alignment portion, but xSize I don't think will be > possible to implement at all. Write a wrapper that allocates the requested size plus an 8-byte header each time an allocation is requested. Use the header space to store the size of the allocation. Dan. > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
