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Revision cff0d1e8e68e6360328fa39e01e8566747185947 authored by Peter Dillinger on 18 March 2022, 18:06:17 UTC, committed by Facebook GitHub Bot on 18 March 2022, 18:06:17 UTC 
New backup meta schema, with file temperatures (#9660)
 
Summary:
The primary goal of this change is to add support for backing up and
restoring (applying on restore) file temperature metadata, without
committing to either the DB manifest or the FS reported "current"
temperatures being exclusive "source of truth".

To achieve this goal, we need to add temperature information to backup
metadata, which requires updated backup meta schema. Fortunately I
prepared for this in https://github.com/facebook/rocksdb/issues/8069, which began forward compatibility in version
6.19.0 for this kind of schema update. (Previously, backup meta schema
was not extensible! Making this schema update public will allow some
other "nice to have" features like taking backups with hard links, and
avoiding crc32c checksum computation when another checksum is already
available.) While schema version 2 is newly public, the default schema
version is still 1. Until we change the default, users will need to set
to 2 to enable features like temperature data backup+restore. New
metadata like temperature information will be ignored with a warning
in versions before this change and since 6.19.0. The metadata is
considered ignorable because a functioning DB can be restored without
it.

Some detail:
* Some renaming because "future schema" is now just public schema 2.
* Initialize some atomics in TestFs (linter reported)
* Add temperature hint support to SstFileDumper (used by BackupEngine)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9660

Test Plan:
related unit test majorly updated for the new functionality,
including some shared testing support for tracking temperatures in a FS.

Some other tests and testing hooks into production code also updated for
making the backup meta schema change public.

Reviewed By: ajkr

Differential Revision: D34686968

Pulled By: pdillinger

fbshipit-source-id: 3ac1fa3e67ee97ca8a5103d79cc87d872c1d862a
1 parent 3bdbf67
Raw File
io_posix_test.cc 
// Copyright (c) 2020-present, Facebook, Inc.  All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).

#include "test_util/testharness.h"

#ifdef ROCKSDB_LIB_IO_POSIX
#include "env/io_posix.h"

namespace ROCKSDB_NAMESPACE {

#ifdef OS_LINUX
class LogicalBlockSizeCacheTest : public testing::Test {};

// Tests the caching behavior.
TEST_F(LogicalBlockSizeCacheTest, Cache) {
  int ncall = 0;
  auto get_fd_block_size = [&](int fd) {
    ncall++;
    return fd;
  };
  std::map<std::string, int> dir_fds{
      {"/", 0},
      {"/db", 1},
      {"/db1", 2},
      {"/db2", 3},
  };
  auto get_dir_block_size = [&](const std::string& dir, size_t* size) {
    ncall++;
    *size = dir_fds[dir];
    return Status::OK();
  };
  LogicalBlockSizeCache cache(get_fd_block_size, get_dir_block_size);
  ASSERT_EQ(0, ncall);
  ASSERT_EQ(0, cache.Size());

  ASSERT_EQ(6, cache.GetLogicalBlockSize("/sst", 6));
  ASSERT_EQ(1, ncall);
  ASSERT_EQ(7, cache.GetLogicalBlockSize("/db/sst1", 7));
  ASSERT_EQ(2, ncall);
  ASSERT_EQ(8, cache.GetLogicalBlockSize("/db/sst2", 8));
  ASSERT_EQ(3, ncall);

  ASSERT_OK(cache.RefAndCacheLogicalBlockSize({"/", "/db1/", "/db2"}));
  ASSERT_EQ(3, cache.Size());
  ASSERT_TRUE(cache.Contains("/"));
  ASSERT_TRUE(cache.Contains("/db1"));
  ASSERT_TRUE(cache.Contains("/db2"));
  ASSERT_EQ(6, ncall);
  // Block size for / is cached.
  ASSERT_EQ(0, cache.GetLogicalBlockSize("/sst", 6));
  ASSERT_EQ(6, ncall);
  // No cached size for /db.
  ASSERT_EQ(7, cache.GetLogicalBlockSize("/db/sst1", 7));
  ASSERT_EQ(7, ncall);
  ASSERT_EQ(8, cache.GetLogicalBlockSize("/db/sst2", 8));
  ASSERT_EQ(8, ncall);
  // Block size for /db1 is cached.
  ASSERT_EQ(2, cache.GetLogicalBlockSize("/db1/sst1", 4));
  ASSERT_EQ(8, ncall);
  ASSERT_EQ(2, cache.GetLogicalBlockSize("/db1/sst2", 5));
  ASSERT_EQ(8, ncall);
  // Block size for /db2 is cached.
  ASSERT_EQ(3, cache.GetLogicalBlockSize("/db2/sst1", 6));
  ASSERT_EQ(8, ncall);
  ASSERT_EQ(3, cache.GetLogicalBlockSize("/db2/sst2", 7));
  ASSERT_EQ(8, ncall);

  ASSERT_OK(cache.RefAndCacheLogicalBlockSize({"/db"}));
  ASSERT_EQ(4, cache.Size());
  ASSERT_TRUE(cache.Contains("/"));
  ASSERT_TRUE(cache.Contains("/db1"));
  ASSERT_TRUE(cache.Contains("/db2"));
  ASSERT_TRUE(cache.Contains("/db"));

  ASSERT_EQ(9, ncall);
  // Block size for /db is cached.
  ASSERT_EQ(1, cache.GetLogicalBlockSize("/db/sst1", 7));
  ASSERT_EQ(9, ncall);
  ASSERT_EQ(1, cache.GetLogicalBlockSize("/db/sst2", 8));
  ASSERT_EQ(9, ncall);
}

// Tests the reference counting behavior.
TEST_F(LogicalBlockSizeCacheTest, Ref) {
  int ncall = 0;
  auto get_fd_block_size = [&](int fd) {
    ncall++;
    return fd;
  };
  std::map<std::string, int> dir_fds{
      {"/db", 0},
  };
  auto get_dir_block_size = [&](const std::string& dir, size_t* size) {
    ncall++;
    *size = dir_fds[dir];
    return Status::OK();
  };
  LogicalBlockSizeCache cache(get_fd_block_size, get_dir_block_size);

  ASSERT_EQ(0, ncall);

  ASSERT_EQ(1, cache.GetLogicalBlockSize("/db/sst0", 1));
  ASSERT_EQ(1, ncall);

  ASSERT_OK(cache.RefAndCacheLogicalBlockSize({"/db"}));
  ASSERT_EQ(2, ncall);
  ASSERT_EQ(1, cache.GetRefCount("/db"));
  // Block size for /db is cached. Ref count = 1.
  ASSERT_EQ(0, cache.GetLogicalBlockSize("/db/sst1", 1));
  ASSERT_EQ(2, ncall);

  // Ref count = 2, but won't recompute the cached buffer size.
  ASSERT_OK(cache.RefAndCacheLogicalBlockSize({"/db"}));
  ASSERT_EQ(2, cache.GetRefCount("/db"));
  ASSERT_EQ(2, ncall);

  // Ref count = 1.
  cache.UnrefAndTryRemoveCachedLogicalBlockSize({"/db"});
  ASSERT_EQ(1, cache.GetRefCount("/db"));
  // Block size for /db is still cached.
  ASSERT_EQ(0, cache.GetLogicalBlockSize("/db/sst2", 1));
  ASSERT_EQ(2, ncall);

  // Ref count = 0 and cached buffer size for /db is removed.
  cache.UnrefAndTryRemoveCachedLogicalBlockSize({"/db"});
  ASSERT_EQ(0, cache.Size());
  ASSERT_EQ(1, cache.GetLogicalBlockSize("/db/sst0", 1));
  ASSERT_EQ(3, ncall);
}
#endif

}  // namespace ROCKSDB_NAMESPACE
#endif

int main(int argc, char** argv) {
  ::testing::InitGoogleTest(&argc, argv);
  return RUN_ALL_TESTS();
}
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