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|#define MEM_BUF_INIT_SIZE (2*1024)
* Here is how one would Comm::Write an object without MemBuffer:
* -- allocate:
* buf = malloc(big_enough);
* -- "pack":
* snprintf object(s) piece-by-piece constantly checking for overflows
* and maintaining (buf+offset);
* -- write
* Comm::Write(buf, free, ...);
* The whole "packing" idea is quite messy: We are given a buffer of fixed
* size and we have to check all the time that we still fit. Sounds logical.
* However, what happens if we have more data? If we are lucky to stop before
* we overrun any buffers, we still may have garbage (e.g. half of ETag) in
* the buffer.
* MemBuffer is a memory-resident buffer with printf()-like interface. It
* hides all offest handling and overflow checking. Moreover, it has a
* build-in control that no partial data has been written.
* MemBuffer is designed to handle relatively small data. It starts with a
* small buffer of configurable size to avoid allocating huge buffers all the
* time. MemBuffer doubles the buffer when needed. It assert()s that it will
* not grow larger than a configurable limit. MemBuffer has virtually no
* overhead (and can even reduce memory consumption) compared to old
* "packing" approach.
* MemBuffer eliminates both "packing" mess and truncated data:
* -- setup
* MemBuf buf;
* -- required init with optional size tuning (see #defines for defaults)
* buf.init(initial-size, absolute-maximum);
* -- "pack" (no need to handle offsets or check for overflows)
* -- write
* Comm::Write(fd, buf, callback);
* -- *iff* you did not give the buffer away, free it yourself
* -- buf.clean();
Definition at line 82 of file MemBuf.cc.
Referenced by MemBuf::init().
|#define MEM_BUF_MAX_SIZE (2*1000*1024*1024)