Fix discard stats moved by GC bug (#929) #2
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* Fix discard stats moved by GC bug The discard stats are stored like normal keys in badger, which means if the size of the value of discard stats key is greater the value threshold it will be stored in the value log. When value log GC happens, we insert the same key in badger with a !badger!move prefix which points to the new value log file. So when searching for the value of a key, if the value points to a value log file which doesn't exist, we search for the same key with !badger!move prefix. The above logic was missing from the populateDiscardStats function. The earlier implementation would never search for the key with !badger!move prefix. It would return error on the first attempt to find the key. This commit ensures we search for a key with prefix badger move if the value for the existing key pointed to a value log file that no longer exists.
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The discard stats are stored like normal keys in badger, which means if
the size of the value of discard stats key is greater the value threshold it
will be stored in the value log. When value log GC happens, we insert
the same key in badger with a !badger!move prefix which points to the
new value log file. So when searching for the value of a key, if the value
points to a value log file which doesn't exist, we search for the same
key with !badger!move prefix.
The above logic was missing from the populateDiscardStats function. The
earlier implementation would never search for the key with !badger!move
prefix. It would return error on the first attempt to find the key. This
commit ensures we search for a key with prefix badger move if the value
for the existing key pointed to a value log file that no longer exists.