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rocksdb/utilities/transactions/write_prepared_transaction_test.cc
Maysam Yabandeh 60beefd6e0 WritePrepared Txn: Advance seq one per batch 
Summary:
By default the seq number in DB is increased once per written key. WritePrepared txns requires the seq to be increased once per the entire batch so that the seq would be used as the prepare timestamp by which the transaction is identified. Also we need to increase seq for the commit marker since it would give a unique id to the commit timestamp of transactions.

Two unit tests are added to verify our understanding of how the seq should be increased. The recovery path requires much more work and is left to another patch.
Closes https://github.com/facebook/rocksdb/pull/2885

Differential Revision: D5837843

Pulled By: maysamyabandeh

fbshipit-source-id: a08960b93d727e1cf438c254d0c2636fb133cc1c
2017-09-18 14:45:08 -07:00

777 lines
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// Copyright (c) 2011-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).
#ifndef ROCKSDB_LITE
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include "utilities/transactions/transaction_test.h"
#include <inttypes.h>
#include <algorithm>
#include <functional>
#include <string>
#include <thread>
#include "db/db_impl.h"
#include "rocksdb/db.h"
#include "rocksdb/options.h"
#include "rocksdb/utilities/transaction.h"
#include "rocksdb/utilities/transaction_db.h"
#include "table/mock_table.h"
#include "util/fault_injection_test_env.h"
#include "util/random.h"
#include "util/string_util.h"
#include "util/sync_point.h"
#include "util/testharness.h"
#include "util/testutil.h"
#include "util/transaction_test_util.h"
#include "utilities/merge_operators.h"
#include "utilities/merge_operators/string_append/stringappend.h"
#include "utilities/transactions/pessimistic_transaction_db.h"
#include "port/port.h"
using std::string;
namespace rocksdb {
using CommitEntry = WritePreparedTxnDB::CommitEntry;
using CommitEntry64b = WritePreparedTxnDB::CommitEntry64b;
using CommitEntry64bFormat = WritePreparedTxnDB::CommitEntry64bFormat;
TEST(PreparedHeap, BasicsTest) {
WritePreparedTxnDB::PreparedHeap heap;
heap.push(14l);
// Test with one element
ASSERT_EQ(14l, heap.top());
heap.push(24l);
heap.push(34l);
// Test that old min is still on top
ASSERT_EQ(14l, heap.top());
heap.push(13l);
// Test that the new min will be on top
ASSERT_EQ(13l, heap.top());
// Test that it is persistent
ASSERT_EQ(13l, heap.top());
heap.push(44l);
heap.push(54l);
heap.push(64l);
heap.push(74l);
heap.push(84l);
// Test that old min is still on top
ASSERT_EQ(13l, heap.top());
heap.erase(24l);
// Test that old min is still on top
ASSERT_EQ(13l, heap.top());
heap.erase(14l);
// Test that old min is still on top
ASSERT_EQ(13l, heap.top());
heap.erase(13l);
// Test that the new comes to the top after multiple erase
ASSERT_EQ(34l, heap.top());
heap.erase(34l);
// Test that the new comes to the top after single erase
ASSERT_EQ(44l, heap.top());
heap.erase(54l);
ASSERT_EQ(44l, heap.top());
heap.pop(); // pop 44l
// Test that the erased items are ignored after pop
ASSERT_EQ(64l, heap.top());
heap.erase(44l);
// Test that erasing an already popped item would work
ASSERT_EQ(64l, heap.top());
heap.erase(84l);
ASSERT_EQ(64l, heap.top());
heap.push(85l);
heap.push(86l);
heap.push(87l);
heap.push(88l);
heap.push(89l);
heap.erase(87l);
heap.erase(85l);
heap.erase(89l);
heap.erase(86l);
heap.erase(88l);
// Test top remians the same after a ranodm order of many erases
ASSERT_EQ(64l, heap.top());
heap.pop();
// Test that pop works with a series of random pending erases
ASSERT_EQ(74l, heap.top());
ASSERT_FALSE(heap.empty());
heap.pop();
// Test that empty works
ASSERT_TRUE(heap.empty());
}
TEST(CommitEntry64b, BasicTest) {
const size_t INDEX_BITS = static_cast<size_t>(21);
const size_t INDEX_SIZE = static_cast<size_t>(1ull << INDEX_BITS);
const CommitEntry64bFormat FORMAT(static_cast<size_t>(INDEX_BITS));
// zero-initialized CommitEntry64b should inidcate an empty entry
CommitEntry64b empty_entry64b;
uint64_t empty_index = 11ul;
CommitEntry empty_entry;
bool ok = empty_entry64b.Parse(empty_index, &empty_entry, FORMAT);
ASSERT_FALSE(ok);
// the zero entry is reserved for un-initialized entries
const size_t MAX_COMMIT = (1 << FORMAT.COMMIT_BITS) - 1 - 1;
// Samples over the numbers that are covered by that many index bits
std::array<uint64_t, 4> is = {{0, 1, INDEX_SIZE / 2 + 1, INDEX_SIZE - 1}};
// Samples over the numbers that are covered by that many commit bits
std::array<uint64_t, 4> ds = {{0, 1, MAX_COMMIT / 2 + 1, MAX_COMMIT}};
// Iterate over prepare numbers that have i) cover all bits of a sequence
// number, and ii) include some bits that fall into the range of index or
// commit bits
for (uint64_t base = 1; base < kMaxSequenceNumber; base *= 2) {
for (uint64_t i : is) {
for (uint64_t d : ds) {
uint64_t p = base + i + d;
for (uint64_t c : {p, p + d / 2, p + d}) {
uint64_t index = p % INDEX_SIZE;
CommitEntry before(p, c), after;
CommitEntry64b entry64b(before, FORMAT);
ok = entry64b.Parse(index, &after, FORMAT);
ASSERT_TRUE(ok);
if (!(before == after)) {
printf("base %" PRIu64 " i %" PRIu64 " d %" PRIu64 " p %" PRIu64
" c %" PRIu64 " index %" PRIu64 "\n",
base, i, d, p, c, index);
}
ASSERT_EQ(before, after);
}
}
}
}
}
class WritePreparedTxnDBMock : public WritePreparedTxnDB {
public:
WritePreparedTxnDBMock(DBImpl* db_impl, TransactionDBOptions& opt)
: WritePreparedTxnDB(db_impl, opt) {}
WritePreparedTxnDBMock(DBImpl* db_impl, TransactionDBOptions& opt,
size_t snapshot_cache_size)
: WritePreparedTxnDB(db_impl, opt, snapshot_cache_size) {}
WritePreparedTxnDBMock(DBImpl* db_impl, TransactionDBOptions& opt,
size_t snapshot_cache_size, size_t commit_cache_size)
: WritePreparedTxnDB(db_impl, opt, snapshot_cache_size,
commit_cache_size) {}
void SetDBSnapshots(const std::vector<SequenceNumber>& snapshots) {
snapshots_ = snapshots;
}
void TakeSnapshot(SequenceNumber seq) { snapshots_.push_back(seq); }
protected:
virtual const std::vector<SequenceNumber> GetSnapshotListFromDB(
SequenceNumber /* unused */) override {
return snapshots_;
}
private:
std::vector<SequenceNumber> snapshots_;
};
class WritePreparedTransactionTest : public TransactionTest {
protected:
// If expect_update is set, check if it actually updated old_commit_map_. If
// it did not and yet suggested not to check the next snapshot, do the
// opposite to check if it was not a bad suggstion.
void MaybeUpdateOldCommitMapTestWithNext(uint64_t prepare, uint64_t commit,
uint64_t snapshot,
uint64_t next_snapshot,
bool expect_update) {
WritePreparedTxnDB* wp_db = dynamic_cast<WritePreparedTxnDB*>(db);
// reset old_commit_map_empty_ so that its value indicate whether
// old_commit_map_ was updated
wp_db->old_commit_map_empty_ = true;
bool check_next = wp_db->MaybeUpdateOldCommitMap(prepare, commit, snapshot,
snapshot < next_snapshot);
if (expect_update == wp_db->old_commit_map_empty_) {
printf("prepare: %" PRIu64 " commit: %" PRIu64 " snapshot: %" PRIu64
" next: %" PRIu64 "\n",
prepare, commit, snapshot, next_snapshot);
}
EXPECT_EQ(!expect_update, wp_db->old_commit_map_empty_);
if (!check_next && wp_db->old_commit_map_empty_) {
// do the oppotisite to make sure it was not a bad suggestion
const bool dont_care_bool = true;
wp_db->MaybeUpdateOldCommitMap(prepare, commit, next_snapshot,
dont_care_bool);
if (!wp_db->old_commit_map_empty_) {
printf("prepare: %" PRIu64 " commit: %" PRIu64 " snapshot: %" PRIu64
" next: %" PRIu64 "\n",
prepare, commit, snapshot, next_snapshot);
}
EXPECT_TRUE(wp_db->old_commit_map_empty_);
}
}
// Test that a CheckAgainstSnapshots thread reading old_snapshots will not
// miss a snapshot because of a concurrent update by UpdateSnapshots that is
// writing new_snapshots. Both threads are broken at two points. The sync
// points to enforce them are specified by a1, a2, b1, and b2. CommitEntry
// entry is expected to be vital for one of the snapshots that is common
// between the old and new list of snapshots.
void SnapshotConcurrentAccessTestInternal(
WritePreparedTxnDB* wp_db,
const std::vector<SequenceNumber>& old_snapshots,
const std::vector<SequenceNumber>& new_snapshots, CommitEntry& entry,
SequenceNumber& version, size_t a1, size_t a2, size_t b1, size_t b2) {
// First reset the snapshot list
const std::vector<SequenceNumber> empty_snapshots;
wp_db->old_commit_map_empty_ = true;
wp_db->UpdateSnapshots(empty_snapshots, ++version);
// Then initialize it with the old_snapshots
wp_db->UpdateSnapshots(old_snapshots, ++version);
// Starting from the first thread, cut each thread at two points
rocksdb::SyncPoint::GetInstance()->LoadDependency({
{"WritePreparedTxnDB::CheckAgainstSnapshots:p:" + std::to_string(a1),
"WritePreparedTxnDB::UpdateSnapshots:s:start"},
{"WritePreparedTxnDB::UpdateSnapshots:p:" + std::to_string(b1),
"WritePreparedTxnDB::CheckAgainstSnapshots:s:" + std::to_string(a1)},
{"WritePreparedTxnDB::CheckAgainstSnapshots:p:" + std::to_string(a2),
"WritePreparedTxnDB::UpdateSnapshots:s:" + std::to_string(b1)},
{"WritePreparedTxnDB::UpdateSnapshots:p:" + std::to_string(b2),
"WritePreparedTxnDB::CheckAgainstSnapshots:s:" + std::to_string(a2)},
{"WritePreparedTxnDB::CheckAgainstSnapshots:p:end",
"WritePreparedTxnDB::UpdateSnapshots:s:" + std::to_string(b2)},
});
rocksdb::SyncPoint::GetInstance()->EnableProcessing();
{
ASSERT_TRUE(wp_db->old_commit_map_empty_);
rocksdb::port::Thread t1(
[&]() { wp_db->UpdateSnapshots(new_snapshots, version); });
rocksdb::port::Thread t2([&]() { wp_db->CheckAgainstSnapshots(entry); });
t1.join();
t2.join();
ASSERT_FALSE(wp_db->old_commit_map_empty_);
}
rocksdb::SyncPoint::GetInstance()->DisableProcessing();
wp_db->old_commit_map_empty_ = true;
wp_db->UpdateSnapshots(empty_snapshots, ++version);
wp_db->UpdateSnapshots(old_snapshots, ++version);
// Starting from the second thread, cut each thread at two points
rocksdb::SyncPoint::GetInstance()->LoadDependency({
{"WritePreparedTxnDB::UpdateSnapshots:p:" + std::to_string(a1),
"WritePreparedTxnDB::CheckAgainstSnapshots:s:start"},
{"WritePreparedTxnDB::CheckAgainstSnapshots:p:" + std::to_string(b1),
"WritePreparedTxnDB::UpdateSnapshots:s:" + std::to_string(a1)},
{"WritePreparedTxnDB::UpdateSnapshots:p:" + std::to_string(a2),
"WritePreparedTxnDB::CheckAgainstSnapshots:s:" + std::to_string(b1)},
{"WritePreparedTxnDB::CheckAgainstSnapshots:p:" + std::to_string(b2),
"WritePreparedTxnDB::UpdateSnapshots:s:" + std::to_string(a2)},
{"WritePreparedTxnDB::UpdateSnapshots:p:end",
"WritePreparedTxnDB::CheckAgainstSnapshots:s:" + std::to_string(b2)},
});
rocksdb::SyncPoint::GetInstance()->EnableProcessing();
{
ASSERT_TRUE(wp_db->old_commit_map_empty_);
rocksdb::port::Thread t1(
[&]() { wp_db->UpdateSnapshots(new_snapshots, version); });
rocksdb::port::Thread t2([&]() { wp_db->CheckAgainstSnapshots(entry); });
t1.join();
t2.join();
ASSERT_FALSE(wp_db->old_commit_map_empty_);
}
rocksdb::SyncPoint::GetInstance()->DisableProcessing();
}
};
INSTANTIATE_TEST_CASE_P(WritePreparedTransactionTest,
WritePreparedTransactionTest,
::testing::Values(std::make_tuple(false, true,
WRITE_PREPARED)));
TEST_P(WritePreparedTransactionTest, CommitMapTest) {
WritePreparedTxnDB* wp_db = dynamic_cast<WritePreparedTxnDB*>(db);
assert(wp_db);
assert(wp_db->db_impl_);
size_t size = wp_db->COMMIT_CACHE_SIZE;
CommitEntry c = {5, 12}, e;
bool evicted = wp_db->AddCommitEntry(c.prep_seq % size, c, &e);
ASSERT_FALSE(evicted);
// Should be able to read the same value
CommitEntry64b dont_care;
bool found = wp_db->GetCommitEntry(c.prep_seq % size, &dont_care, &e);
ASSERT_TRUE(found);
ASSERT_EQ(c, e);
// Should be able to distinguish between overlapping entries
found = wp_db->GetCommitEntry((c.prep_seq + size) % size, &dont_care, &e);
ASSERT_TRUE(found);
ASSERT_NE(c.prep_seq + size, e.prep_seq);
// Should be able to detect non-existent entry
found = wp_db->GetCommitEntry((c.prep_seq + 1) % size, &dont_care, &e);
ASSERT_FALSE(found);
// Reject an invalid exchange
CommitEntry e2 = {c.prep_seq + size, c.commit_seq + size};
CommitEntry64b e2_64b(e2, wp_db->FORMAT);
bool exchanged = wp_db->ExchangeCommitEntry(e2.prep_seq % size, e2_64b, e);
ASSERT_FALSE(exchanged);
// check whether it did actually reject that
found = wp_db->GetCommitEntry(e2.prep_seq % size, &dont_care, &e);
ASSERT_TRUE(found);
ASSERT_EQ(c, e);
// Accept a valid exchange
CommitEntry64b c_64b(c, wp_db->FORMAT);
CommitEntry e3 = {c.prep_seq + size, c.commit_seq + size + 1};
exchanged = wp_db->ExchangeCommitEntry(c.prep_seq % size, c_64b, e3);
ASSERT_TRUE(exchanged);
// check whether it did actually accepted that
found = wp_db->GetCommitEntry(c.prep_seq % size, &dont_care, &e);
ASSERT_TRUE(found);
ASSERT_EQ(e3, e);
// Rewrite an entry
CommitEntry e4 = {e3.prep_seq + size, e3.commit_seq + size + 1};
evicted = wp_db->AddCommitEntry(e4.prep_seq % size, e4, &e);
ASSERT_TRUE(evicted);
ASSERT_EQ(e3, e);
found = wp_db->GetCommitEntry(e4.prep_seq % size, &dont_care, &e);
ASSERT_TRUE(found);
ASSERT_EQ(e4, e);
}
TEST_P(WritePreparedTransactionTest, MaybeUpdateOldCommitMap) {
// If prepare <= snapshot < commit we should keep the entry around since its
// nonexistence could be interpreted as committed in the snapshot while it is
// not true. We keep such entries around by adding them to the
// old_commit_map_.
uint64_t p /*prepare*/, c /*commit*/, s /*snapshot*/, ns /*next_snapshot*/;
p = 10l, c = 15l, s = 20l, ns = 21l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
// If we do not expect the old commit map to be updated, try also with a next
// snapshot that is expected to update the old commit map. This would test
// that MaybeUpdateOldCommitMap would not prevent us from checking the next
// snapshot that must be checked.
p = 10l, c = 15l, s = 20l, ns = 11l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
p = 10l, c = 20l, s = 20l, ns = 19l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
p = 10l, c = 20l, s = 20l, ns = 21l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
p = 20l, c = 20l, s = 20l, ns = 21l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
p = 20l, c = 20l, s = 20l, ns = 19l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
p = 10l, c = 25l, s = 20l, ns = 21l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, true);
p = 20l, c = 25l, s = 20l, ns = 21l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, true);
p = 21l, c = 25l, s = 20l, ns = 22l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
p = 21l, c = 25l, s = 20l, ns = 19l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
}
TEST_P(WritePreparedTransactionTest, CheckAgainstSnapshotsTest) {
std::vector<SequenceNumber> snapshots = {100l, 200l, 300l, 400l, 500l,
600l, 700l, 800l, 900l};
const size_t snapshot_cache_bits = 2;
// Safety check to express the intended size in the test. Can be adjusted if
// the snapshots lists changed.
assert((1ul << snapshot_cache_bits) * 2 + 1 == snapshots.size());
DBImpl* mock_db = new DBImpl(options, dbname);
std::unique_ptr<WritePreparedTxnDBMock> wp_db(
new WritePreparedTxnDBMock(mock_db, txn_db_options, snapshot_cache_bits));
SequenceNumber version = 1000l;
ASSERT_EQ(0, wp_db->snapshots_total_);
wp_db->UpdateSnapshots(snapshots, version);
ASSERT_EQ(snapshots.size(), wp_db->snapshots_total_);
// seq numbers are chosen so that we have two of them between each two
// snapshots. If the diff of two consecuitive seq is more than 5, there is a
// snapshot between them.
std::vector<SequenceNumber> seqs = {50l, 55l, 150l, 155l, 250l, 255l, 350l,
355l, 450l, 455l, 550l, 555l, 650l, 655l,
750l, 755l, 850l, 855l, 950l, 955l};
assert(seqs.size() > 1);
for (size_t i = 0; i < seqs.size() - 1; i++) {
wp_db->old_commit_map_empty_ = true; // reset
CommitEntry commit_entry = {seqs[i], seqs[i + 1]};
wp_db->CheckAgainstSnapshots(commit_entry);
// Expect update if there is snapshot in between the prepare and commit
bool expect_update = commit_entry.commit_seq - commit_entry.prep_seq > 5 &&
commit_entry.commit_seq >= snapshots.front() &&
commit_entry.prep_seq <= snapshots.back();
ASSERT_EQ(expect_update, !wp_db->old_commit_map_empty_);
}
}
// Return true if the ith bit is set in combination represented by comb
bool IsInCombination(size_t i, size_t comb) { return comb & (size_t(1) << i); }
// This test is too slow for travis
#ifndef TRAVIS
// Test that CheckAgainstSnapshots will not miss a live snapshot if it is run in
// parallel with UpdateSnapshots.
TEST_P(WritePreparedTransactionTest, SnapshotConcurrentAccessTest) {
// We have a sync point in the method under test after checking each snapshot.
// If you increase the max number of snapshots in this test, more sync points
// in the methods must also be added.
const std::vector<SequenceNumber> snapshots = {10l, 20l, 30l, 40l, 50l,
60l, 70l, 80l, 90l, 100l};
const size_t snapshot_cache_bits = 2;
// Safety check to express the intended size in the test. Can be adjusted if
// the snapshots lists changed.
assert((1ul << snapshot_cache_bits) * 2 + 2 == snapshots.size());
SequenceNumber version = 1000l;
// Choose the cache size so that the new snapshot list could replace all the
// existing items in the cache and also have some overflow.
DBImpl* mock_db = new DBImpl(options, dbname);
std::unique_ptr<WritePreparedTxnDBMock> wp_db(
new WritePreparedTxnDBMock(mock_db, txn_db_options, snapshot_cache_bits));
// Add up to 2 items that do not fit into the cache
for (size_t old_size = 1; old_size <= wp_db->SNAPSHOT_CACHE_SIZE + 2;
old_size++) {
const std::vector<SequenceNumber> old_snapshots(
snapshots.begin(), snapshots.begin() + old_size);
// Each member of old snapshot might or might not appear in the new list. We
// create a common_snapshots for each combination.
size_t new_comb_cnt = size_t(1) << old_size;
for (size_t new_comb = 0; new_comb < new_comb_cnt; new_comb++) {
printf("."); // To signal progress
fflush(stdout);
std::vector<SequenceNumber> common_snapshots;
for (size_t i = 0; i < old_snapshots.size(); i++) {
if (IsInCombination(i, new_comb)) {
common_snapshots.push_back(old_snapshots[i]);
}
}
// And add some new snapshots to the common list
for (size_t added_snapshots = 0;
added_snapshots <= snapshots.size() - old_snapshots.size();
added_snapshots++) {
std::vector<SequenceNumber> new_snapshots = common_snapshots;
for (size_t i = 0; i < added_snapshots; i++) {
new_snapshots.push_back(snapshots[old_snapshots.size() + i]);
}
for (auto it = common_snapshots.begin(); it != common_snapshots.end();
it++) {
auto snapshot = *it;
// Create a commit entry that is around the snapshot and thus should
// be not be discarded
CommitEntry entry = {static_cast<uint64_t>(snapshot - 1),
snapshot + 1};
// The critical part is when iterating the snapshot cache. Afterwards,
// we are operating under the lock
size_t a_range =
std::min(old_snapshots.size(), wp_db->SNAPSHOT_CACHE_SIZE) + 1;
size_t b_range =
std::min(new_snapshots.size(), wp_db->SNAPSHOT_CACHE_SIZE) + 1;
// Break each thread at two points
for (size_t a1 = 1; a1 <= a_range; a1++) {
for (size_t a2 = a1 + 1; a2 <= a_range; a2++) {
for (size_t b1 = 1; b1 <= b_range; b1++) {
for (size_t b2 = b1 + 1; b2 <= b_range; b2++) {
SnapshotConcurrentAccessTestInternal(
wp_db.get(), old_snapshots, new_snapshots, entry, version,
a1, a2, b1, b2);
}
}
}
}
}
}
}
}
printf("\n");
}
#endif
// This test clarifies the contract of AdvanceMaxEvictedSeq method
TEST_P(WritePreparedTransactionTest, AdvanceMaxEvictedSeqBasicTest) {
DBImpl* mock_db = new DBImpl(options, dbname);
std::unique_ptr<WritePreparedTxnDBMock> wp_db(
new WritePreparedTxnDBMock(mock_db, txn_db_options));
// 1. Set the initial values for max, prepared, and snapshots
SequenceNumber zero_max = 0l;
// Set the initial list of prepared txns
const std::vector<SequenceNumber> initial_prepared = {10, 30, 50, 100,
150, 200, 250};
for (auto p : initial_prepared) {
wp_db->AddPrepared(p);
}
// This updates the max value and also set old prepared
SequenceNumber init_max = 100;
wp_db->AdvanceMaxEvictedSeq(zero_max, init_max);
const std::vector<SequenceNumber> initial_snapshots = {20, 40};
wp_db->SetDBSnapshots(initial_snapshots);
// This will update the internal cache of snapshots from the DB
wp_db->UpdateSnapshots(initial_snapshots, init_max);
// 2. Invoke AdvanceMaxEvictedSeq
const std::vector<SequenceNumber> latest_snapshots = {20, 110, 220, 300};
wp_db->SetDBSnapshots(latest_snapshots);
SequenceNumber new_max = 200;
wp_db->AdvanceMaxEvictedSeq(init_max, new_max);
// 3. Verify that the state matches with AdvanceMaxEvictedSeq contract
// a. max should be updated to new_max
ASSERT_EQ(wp_db->max_evicted_seq_, new_max);
// b. delayed prepared should contain every txn <= max and prepared should
// only contian txns > max
auto it = initial_prepared.begin();
for (; it != initial_prepared.end() && *it <= new_max; it++) {
ASSERT_EQ(1, wp_db->delayed_prepared_.erase(*it));
}
ASSERT_TRUE(wp_db->delayed_prepared_.empty());
for (; it != initial_prepared.end() && !wp_db->prepared_txns_.empty();
it++, wp_db->prepared_txns_.pop()) {
ASSERT_EQ(*it, wp_db->prepared_txns_.top());
}
ASSERT_TRUE(it == initial_prepared.end());
ASSERT_TRUE(wp_db->prepared_txns_.empty());
// c. snapshots should contain everything below new_max
auto sit = latest_snapshots.begin();
for (size_t i = 0; sit != latest_snapshots.end() && *sit <= new_max &&
i < wp_db->snapshots_total_;
sit++, i++) {
ASSERT_TRUE(i < wp_db->snapshots_total_);
// This test is in small scale and the list of snapshots are assumed to be
// within the cache size limit. This is just a safety check to double check
// that assumption.
ASSERT_TRUE(i < wp_db->SNAPSHOT_CACHE_SIZE);
ASSERT_EQ(*sit, wp_db->snapshot_cache_[i]);
}
}
// This test clarfies the existing expectation from the sequence number
// algorithm. It could detect mistakes in updating the code but it is not
// necessarily the one acceptable way. If the algorithm is legitimately changed,
// this unit test should be updated as well.
TEST_P(WritePreparedTransactionTest, SeqAdvanceTest) {
auto pdb = reinterpret_cast<PessimisticTransactionDB*>(db);
DBImpl* db_impl = reinterpret_cast<DBImpl*>(db->GetRootDB());
auto seq = db_impl->GetLatestSequenceNumber();
auto exp_seq = seq;
// Test DB's internal txn. It involves no prepare phase nor a commit marker.
WriteOptions wopts;
auto s = db->Put(wopts, "key", "value");
// Consume one seq per batch
exp_seq++;
ASSERT_OK(s);
seq = db_impl->GetLatestSequenceNumber();
ASSERT_EQ(exp_seq, seq);
// Doing it twice might detect some bugs
s = db->Put(wopts, "key", "value");
exp_seq++;
ASSERT_OK(s);
seq = db_impl->GetLatestSequenceNumber();
ASSERT_EQ(exp_seq, seq);
// Testing directly writing a write batch. Functionality-wise it is equivalent
// to commit without prepare.
WriteBatch wb;
wb.Put("k1", "v1");
wb.Put("k2", "v2");
wb.Put("k3", "v3");
s = pdb->Write(wopts, &wb);
// Consume one seq per batch
exp_seq++;
ASSERT_OK(s);
seq = db_impl->GetLatestSequenceNumber();
ASSERT_EQ(exp_seq, seq);
// A full 2pc txn that also involves a commit marker.
TransactionOptions txn_options;
WriteOptions write_options;
Transaction* txn = db->BeginTransaction(write_options, txn_options);
s = txn->SetName("xid");
ASSERT_OK(s);
s = txn->Put(Slice("foo"), Slice("bar"));
s = txn->Put(Slice("foo2"), Slice("bar2"));
s = txn->Put(Slice("foo3"), Slice("bar3"));
s = txn->Put(Slice("foo4"), Slice("bar4"));
s = txn->Put(Slice("foo5"), Slice("bar5"));
ASSERT_OK(s);
s = txn->Prepare();
ASSERT_OK(s);
// Consume one seq per batch
exp_seq++;
s = txn->Commit();
ASSERT_OK(s);
// Consume one seq per commit marker
exp_seq++;
// Since commit marker does not write to memtable, the last seq number is not
// updated immedaitely. But the advance should be visible after the next
// write.
s = db->Put(wopts, "key", "value");
// Consume one seq per batch
exp_seq++;
ASSERT_OK(s);
seq = db_impl->GetLatestSequenceNumber();
ASSERT_EQ(exp_seq, seq);
// Commit without prepare. It shoudl write to DB without a commit marker.
txn = db->BeginTransaction(write_options, txn_options);
s = txn->SetName("xid2");
ASSERT_OK(s);
s = txn->Put(Slice("foo"), Slice("bar"));
s = txn->Put(Slice("foo2"), Slice("bar2"));
s = txn->Put(Slice("foo3"), Slice("bar3"));
s = txn->Put(Slice("foo4"), Slice("bar4"));
s = txn->Put(Slice("foo5"), Slice("bar5"));
ASSERT_OK(s);
s = txn->Commit();
ASSERT_OK(s);
// Consume one seq per batch
exp_seq++;
seq = db_impl->GetLatestSequenceNumber();
ASSERT_EQ(exp_seq, seq);
pdb->UnregisterTransaction(txn);
delete txn;
}
// Test WritePreparedTxnDB's IsInSnapshot against different ordering of
// snapshot, max_committed_seq_, prepared, and commit entries.
TEST_P(WritePreparedTransactionTest, IsInSnapshotTest) {
WriteOptions wo;
// Use small commit cache to trigger lots of eviction and fast advance of
// max_evicted_seq_
const size_t commit_cache_bits = 3;
// Same for snapshot cache size
const size_t snapshot_cache_bits = 2;
// Take some preliminary snapshots first. This is to stress the data structure
// that holds the old snapshots as it will be designed to be efficient when
// only a few snapshots are below the max_evicted_seq_.
for (int max_snapshots = 1; max_snapshots < 20; max_snapshots++) {
// Leave some gap between the preliminary snapshots and the final snapshot
// that we check. This should test for also different overlapping scnearios
// between the last snapshot and the commits.
for (int max_gap = 1; max_gap < 10; max_gap++) {
// Since we do not actually write to db, we mock the seq as it would be
// increaased by the db. The only exception is that we need db seq to
// advance for our snapshots. for which we apply a dummy put each time we
// increase our mock of seq.
uint64_t seq = 0;
// At each step we prepare a txn and then we commit it in the next txn.
// This emulates the consecuitive transactions that write to the same key
uint64_t cur_txn = 0;
// Number of snapshots taken so far
int num_snapshots = 0;
// Number of gaps applied so far
int gap_cnt = 0;
// The final snapshot that we will inspect
uint64_t snapshot = 0;
bool found_committed = false;
// To stress the data structure that maintain prepared txns, at each cycle
// we add a new prepare txn. These do not mean to be committed for
// snapshot inspection.
std::set<uint64_t> prepared;
// We keep the list of txns comitted before we take the last snaphot.
// These should be the only seq numbers that will be found in the snapshot
std::set<uint64_t> committed_before;
DBImpl* mock_db = new DBImpl(options, dbname);
std::unique_ptr<WritePreparedTxnDBMock> wp_db(new WritePreparedTxnDBMock(
mock_db, txn_db_options, snapshot_cache_bits, commit_cache_bits));
// We continue until max advances a bit beyond the snapshot.
while (!snapshot || wp_db->max_evicted_seq_ < snapshot + 100) {
// do prepare for a transaction
seq++;
wp_db->AddPrepared(seq);
prepared.insert(seq);
// If cur_txn is not started, do prepare for it.
if (!cur_txn) {
seq++;
cur_txn = seq;
wp_db->AddPrepared(cur_txn);
} else { // else commit it
seq++;
wp_db->AddCommitted(cur_txn, seq);
if (!snapshot) {
committed_before.insert(cur_txn);
}
cur_txn = 0;
}
if (num_snapshots < max_snapshots - 1) {
// Take preliminary snapshots
wp_db->TakeSnapshot(seq);
num_snapshots++;
} else if (gap_cnt < max_gap) {
// Wait for some gap before taking the final snapshot
gap_cnt++;
} else if (!snapshot) {
// Take the final snapshot if it is not already taken
snapshot = seq;
wp_db->TakeSnapshot(snapshot);
num_snapshots++;
}
// If the snapshot is taken, verify seq numbers visible to it. We redo
// it at each cycle to test that the system is still sound when
// max_evicted_seq_ advances.
if (snapshot) {
for (uint64_t s = 0; s <= seq; s++) {
bool was_committed =
(committed_before.find(s) != committed_before.end());
bool is_in_snapshot = wp_db->IsInSnapshot(s, snapshot);
if (was_committed != is_in_snapshot) {
printf("max_snapshots %d max_gap %d seq %" PRIu64 " max %" PRIu64
" snapshot %" PRIu64
" gap_cnt %d num_snapshots %d s %" PRIu64 "\n",
max_snapshots, max_gap, seq,
wp_db->max_evicted_seq_.load(), snapshot, gap_cnt,
num_snapshots, s);
}
ASSERT_EQ(was_committed, is_in_snapshot);
found_committed = found_committed || is_in_snapshot;
}
}
}
// Safety check to make sure the test actually ran
ASSERT_TRUE(found_committed);
// As an extra check, check if prepared set will be properly empty after
// they are committed.
if (cur_txn) {
wp_db->AddCommitted(cur_txn, seq);
}
for (auto p : prepared) {
wp_db->AddCommitted(p, seq);
}
ASSERT_TRUE(wp_db->delayed_prepared_.empty());
ASSERT_TRUE(wp_db->prepared_txns_.empty());
}
}
}
} // namespace rocksdb
int main(int argc, char** argv) {
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}
#else
#include <stdio.h>
int main(int argc, char** argv) {
fprintf(stderr,
"SKIPPED as Transactions are not supported in ROCKSDB_LITE\n");
return 0;
}
#endif // ROCKSDB_LITE
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