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Revision 3e7e269292e60c51331839ac00cea409a0439d1d authored by Mark Callaghan on 29 October 2012, 19:04:27 UTC, committed by Mark Callaghan on 30 October 2012, 14:21:37 UTC 
Use timer to measure sleep rather than assume it is 1000 usecs
 
Summary:
This makes the stall timers in MakeRoomForWrite more accurate by timing
the sleeps. From looking at the logs the real sleep times are usually
about 2000 usecs each when SleepForMicros(1000) is called. The modified LOG messages are:
2012/10/29-12:06:33.271984 2b3cc872f700 delaying write 13 usecs for level0_slowdown_writes_trigger
2012/10/29-12:06:34.688939 2b3cc872f700 delaying write 1728 usecs for rate limits with max score 3.83

Task ID: #

Blame Rev:

Test Plan:
run db_bench, look at DB/LOG

Revert Plan:

Database Impact:

Memcache Impact:

Other Notes:

EImportant:

- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -

Reviewers: dhruba

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D6297
1 parent fb8d437
Raw File
hash.cc 
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.

#include <string.h>
#include "util/coding.h"
#include "util/hash.h"

namespace leveldb {

uint32_t Hash(const char* data, size_t n, uint32_t seed) {
  // Similar to murmur hash
  const uint32_t m = 0xc6a4a793;
  const uint32_t r = 24;
  const char* limit = data + n;
  uint32_t h = seed ^ (n * m);

  // Pick up four bytes at a time
  while (data + 4 <= limit) {
    uint32_t w = DecodeFixed32(data);
    data += 4;
    h += w;
    h *= m;
    h ^= (h >> 16);
  }

  // Pick up remaining bytes
  switch (limit - data) {
    case 3:
      h += data[2] << 16;
      // fall through
    case 2:
      h += data[1] << 8;
      // fall through
    case 1:
      h += data[0];
      h *= m;
      h ^= (h >> r);
      break;
  }
  return h;
}


}  // namespace leveldb
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