rocksdb/util/transaction_test_util.cc
Maysam Yabandeh bb2a2ec731 WritePrepared Txn: rollback via commit
Summary:
Currently WritePrepared rolls back a transaction with prepare sequence number prepare_seq by i) write a single rollback batch with rollback_seq, ii) add <rollback_seq, rollback_seq> to commit cache, iii) remove prepare_seq from PrepareHeap.
This is correct assuming that there is no snapshot taken when a transaction is rolled back. This is the case the way MySQL does rollback which is after recovery. Otherwise if max_evicted_seq advances the prepare_seq, the live snapshot might assume data as committed since it does not find them in CommitCache.
The change is to simply add <prepare_seq. rollback_seq> to commit cache before removing prepare_seq from PrepareHeap. In this way if max_evicted_seq advances prpeare_seq, the existing mechanism that we have to check evicted entries against live snapshots will make sure that the live snapshot will not see the data of rolled back transaction.
Closes https://github.com/facebook/rocksdb/pull/3745

Differential Revision: D7696193

Pulled By: maysamyabandeh

fbshipit-source-id: c9a2d46341ddc03554dded1303520a1cab74ef9c
2018-04-20 15:28:19 -07:00

327 lines
10 KiB
C++

// 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 "util/transaction_test_util.h"
#include <inttypes.h>
#include <algorithm>
#include <numeric>
#include <string>
#include <thread>
#include "rocksdb/db.h"
#include "rocksdb/utilities/optimistic_transaction_db.h"
#include "rocksdb/utilities/transaction.h"
#include "rocksdb/utilities/transaction_db.h"
#include "util/random.h"
#include "util/string_util.h"
namespace rocksdb {
RandomTransactionInserter::RandomTransactionInserter(
Random64* rand, const WriteOptions& write_options,
const ReadOptions& read_options, uint64_t num_keys, uint16_t num_sets)
: rand_(rand),
write_options_(write_options),
read_options_(read_options),
num_keys_(num_keys),
num_sets_(num_sets),
txn_id_(0) {}
RandomTransactionInserter::~RandomTransactionInserter() {
if (txn_ != nullptr) {
delete txn_;
}
if (optimistic_txn_ != nullptr) {
delete optimistic_txn_;
}
}
bool RandomTransactionInserter::TransactionDBInsert(
TransactionDB* db, const TransactionOptions& txn_options) {
txn_ = db->BeginTransaction(write_options_, txn_options, txn_);
bool take_snapshot = rand_->OneIn(2);
if (take_snapshot) {
txn_->SetSnapshot();
read_options_.snapshot = txn_->GetSnapshot();
}
auto res = DoInsert(nullptr, txn_, false);
if (take_snapshot) {
read_options_.snapshot = nullptr;
}
return res;
}
bool RandomTransactionInserter::OptimisticTransactionDBInsert(
OptimisticTransactionDB* db,
const OptimisticTransactionOptions& txn_options) {
optimistic_txn_ =
db->BeginTransaction(write_options_, txn_options, optimistic_txn_);
return DoInsert(nullptr, optimistic_txn_, true);
}
bool RandomTransactionInserter::DBInsert(DB* db) {
return DoInsert(db, nullptr, false);
}
Status RandomTransactionInserter::DBGet(
DB* db, Transaction* txn, ReadOptions& read_options, uint16_t set_i,
uint64_t ikey, bool get_for_update, uint64_t* int_value,
std::string* full_key, bool* unexpected_error) {
Status s;
// Five digits (since the largest uint16_t is 65535) plus the NUL
// end char.
char prefix_buf[6];
// Pad prefix appropriately so we can iterate over each set
assert(set_i + 1 <= 9999);
snprintf(prefix_buf, sizeof(prefix_buf), "%.4u", set_i + 1);
// key format: [SET#][random#]
std::string skey = ToString(ikey);
Slice base_key(skey);
*full_key = std::string(prefix_buf) + base_key.ToString();
Slice key(*full_key);
std::string value;
if (txn != nullptr) {
if (get_for_update) {
s = txn->GetForUpdate(read_options, key, &value);
} else {
s = txn->Get(read_options, key, &value);
}
} else {
s = db->Get(read_options, key, &value);
}
if (s.ok()) {
// Found key, parse its value
*int_value = std::stoull(value);
if (*int_value == 0 || *int_value == ULONG_MAX) {
*unexpected_error = true;
fprintf(stderr, "Get returned unexpected value: %s\n", value.c_str());
s = Status::Corruption();
}
} else if (s.IsNotFound()) {
// Have not yet written to this key, so assume its value is 0
*int_value = 0;
s = Status::OK();
}
return s;
}
bool RandomTransactionInserter::DoInsert(DB* db, Transaction* txn,
bool is_optimistic) {
Status s;
WriteBatch batch;
// pick a random number to use to increment a key in each set
uint64_t incr = (rand_->Next() % 100) + 1;
bool unexpected_error = false;
std::vector<uint16_t> set_vec(num_sets_);
std::iota(set_vec.begin(), set_vec.end(), static_cast<uint16_t>(0));
std::random_shuffle(set_vec.begin(), set_vec.end(),
[&](uint64_t r) { return rand_->Uniform(r); });
// For each set, pick a key at random and increment it
for (uint16_t set_i : set_vec) {
uint64_t int_value = 0;
std::string full_key;
uint64_t rand_key = rand_->Next() % num_keys_;
const bool get_for_update = txn ? rand_->OneIn(2) : false;
s = DBGet(db, txn, read_options_, set_i, rand_key, get_for_update,
&int_value, &full_key, &unexpected_error);
Slice key(full_key);
if (!s.ok()) {
// Optimistic transactions should never return non-ok status here.
// Non-optimistic transactions may return write-coflict/timeout errors.
if (is_optimistic || !(s.IsBusy() || s.IsTimedOut() || s.IsTryAgain())) {
fprintf(stderr, "Get returned an unexpected error: %s\n",
s.ToString().c_str());
unexpected_error = true;
}
break;
}
if (s.ok()) {
// Increment key
std::string sum = ToString(int_value + incr);
if (txn != nullptr) {
s = txn->Put(key, sum);
if (!get_for_update && (s.IsBusy() || s.IsTimedOut())) {
// If the initial get was not for update, then the key is not locked
// before put and put could fail due to concurrent writes.
break;
} else if (!s.ok()) {
// Since we did a GetForUpdate, Put should not fail.
fprintf(stderr, "Put returned an unexpected error: %s\n",
s.ToString().c_str());
unexpected_error = true;
}
} else {
batch.Put(key, sum);
}
bytes_inserted_ += key.size() + sum.size();
}
}
if (s.ok()) {
if (txn != nullptr) {
std::hash<std::thread::id> hasher;
char name[64];
snprintf(name, 64, "txn%" ROCKSDB_PRIszt "-%d", hasher(std::this_thread::get_id()),
txn_id_++);
assert(strlen(name) < 64 - 1);
if (!is_optimistic && !rand_->OneIn(10)) {
// also try commit without prpare
txn->SetName(name);
s = txn->Prepare();
assert(s.ok());
}
if (!rand_->OneIn(20)) {
s = txn->Commit();
} else {
// Also try 5% rollback
s = txn->Rollback();
assert(s.ok());
}
assert(is_optimistic || s.ok());
if (!s.ok()) {
if (is_optimistic) {
// Optimistic transactions can have write-conflict errors on commit.
// Any other error is unexpected.
if (!(s.IsBusy() || s.IsTimedOut() || s.IsTryAgain())) {
unexpected_error = true;
}
} else {
// Non-optimistic transactions should only fail due to expiration
// or write failures. For testing purproses, we do not expect any
// write failures.
if (!s.IsExpired()) {
unexpected_error = true;
}
}
if (unexpected_error) {
fprintf(stderr, "Commit returned an unexpected error: %s\n",
s.ToString().c_str());
}
}
} else {
s = db->Write(write_options_, &batch);
if (!s.ok()) {
unexpected_error = true;
fprintf(stderr, "Write returned an unexpected error: %s\n",
s.ToString().c_str());
}
}
} else {
if (txn != nullptr) {
assert(txn->Rollback().ok());
}
}
if (s.ok()) {
success_count_++;
} else {
failure_count_++;
}
last_status_ = s;
// return success if we didn't get any unexpected errors
return !unexpected_error;
}
// Verify that the sum of the keys in each set are equal
Status RandomTransactionInserter::Verify(DB* db, uint16_t num_sets,
uint64_t num_keys_per_set,
bool take_snapshot, Random64* rand) {
uint64_t prev_total = 0;
uint32_t prev_i = 0;
bool prev_assigned = false;
ReadOptions roptions;
if (take_snapshot) {
roptions.snapshot = db->GetSnapshot();
}
std::vector<uint16_t> set_vec(num_sets);
std::iota(set_vec.begin(), set_vec.end(), static_cast<uint16_t>(0));
if (rand) {
std::random_shuffle(set_vec.begin(), set_vec.end(),
[&](uint64_t r) { return rand->Uniform(r); });
}
// For each set of keys with the same prefix, sum all the values
for (uint16_t set_i : set_vec) {
// Five digits (since the largest uint16_t is 65535) plus the NUL
// end char.
char prefix_buf[6];
assert(set_i + 1 <= 9999);
snprintf(prefix_buf, sizeof(prefix_buf), "%.4u", set_i + 1);
uint64_t total = 0;
// Use either point lookup or iterator. Point lookups are slower so we use
// it less often.
if (num_keys_per_set != 0 && rand && rand->OneIn(10)) { // use point lookup
ReadOptions read_options;
for (uint64_t k = 0; k < num_keys_per_set; k++) {
std::string dont_care;
uint64_t int_value = 0;
bool unexpected_error = false;
const bool FOR_UPDATE = false;
Status s = DBGet(db, nullptr, roptions, set_i, k, FOR_UPDATE,
&int_value, &dont_care, &unexpected_error);
assert(s.ok());
assert(!unexpected_error);
total += int_value;
}
} else { // user iterators
Iterator* iter = db->NewIterator(roptions);
for (iter->Seek(Slice(prefix_buf, 4)); iter->Valid(); iter->Next()) {
Slice key = iter->key();
// stop when we reach a different prefix
if (key.ToString().compare(0, 4, prefix_buf) != 0) {
break;
}
Slice value = iter->value();
uint64_t int_value = std::stoull(value.ToString());
if (int_value == 0 || int_value == ULONG_MAX) {
fprintf(stderr, "Iter returned unexpected value: %s\n",
value.ToString().c_str());
return Status::Corruption();
}
total += int_value;
}
delete iter;
}
if (prev_assigned && total != prev_total) {
fprintf(stdout,
"RandomTransactionVerify found inconsistent totals. "
"Set[%" PRIu32 "]: %" PRIu64 ", Set[%" PRIu32 "]: %" PRIu64 " \n",
prev_i, prev_total, set_i, total);
return Status::Corruption();
}
prev_total = total;
prev_i = set_i;
prev_assigned = true;
}
if (take_snapshot) {
db->ReleaseSnapshot(roptions.snapshot);
}
return Status::OK();
}
} // namespace rocksdb
#endif // ROCKSDB_LITE