Fix apc_sma_get_avail_size() to look for a contiguous block of memory to make expunge more reliable #532
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The test failed because before this pull request, the last insert in the loop did not trigger a full_expunge of the whole cache (since apc_sma_get_avail_size() didn't care about contiguous memory blocks). As a result, the last apcu_store() command in the loop failed. With this pull request, the last apcu_store() command is successful. |
nikic
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apc_sma_get_avail_size() is used by apc_cache_default_expunge() to check if enough memory is available to store the next cache entry. Therefore, it is not enough to check the total amount of available memory. The memory must be available in one contiguous block.
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I fixed the things from your review and also clarified the comment in the header file. I hope that's okay, otherwise feel free to comment... |
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apc_sma_get_avail_size() is used by apc_cache_default_expunge() to check whether enough memory is available to store a new cache entry after expired entries are removed. If there is not enough memory available, a real expunge is performed to be able to store the new entry.
The problem is that apc_sma_get_avail_size() only checks the total amount of available memory, which is usually divided into several fragments of memory. However, we need a contiguous block of memory to store a cache entry.
This pull request fixes apc_sma_get_avail_size() to check if a continuous block of memory is available to store a new entry, which solves the problem.
Prior to this fix, the result was that in situations with fragmentation, new cache entries cannot be saved and PHP functions such as apcu_store() return false, which is not the expected behavior.