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foundationdb/fdbserver/KeyValueStoreMemory.actor.cpp

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/*
* KeyValueStoreMemory.actor.cpp
*
* This source file is part of the FoundationDB open source project
*
* Copyright 2013-2022 Apple Inc. and the FoundationDB project authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "fdbclient/Knobs.h"
#include "fdbclient/Notified.h"
#include "fdbclient/SystemData.h"
#include "fdbserver/DeltaTree.h"
#include "fdbserver/IDiskQueue.h"
#include "fdbserver/IKeyValueContainer.h"
#include "fdbserver/IKeyValueStore.h"
#include "fdbserver/RadixTree.h"
#include "flow/ActorCollection.h"
#include "flow/actorcompiler.h" // This must be the last #include.
#define OP_DISK_OVERHEAD (sizeof(OpHeader) + 1)
template <typename Container>
class KeyValueStoreMemory final : public IKeyValueStore, NonCopyable {
public:
KeyValueStoreMemory(IDiskQueue* log,
UID id,
int64_t memoryLimit,
KeyValueStoreType storeType,
bool disableSnapshot,
bool replaceContent,
bool exactRecovery);
// IClosable
Future<Void> getError() const override { return log->getError(); }
Future<Void> onClosed() const override { return log->onClosed(); }
void dispose() override {
recovering.cancel();
log->dispose();
if (reserved_buffer != nullptr) {
delete[] reserved_buffer;
reserved_buffer = nullptr;
}
delete this;
}
void close() override {
recovering.cancel();
log->close();
if (reserved_buffer != nullptr) {
delete[] reserved_buffer;
reserved_buffer = nullptr;
}
delete this;
}
// IKeyValueStore
KeyValueStoreType getType() const override { return type; }
std::tuple<size_t, size_t, size_t> getSize() const override { return data.size(); }
int64_t getAvailableSize() const {
int64_t residentSize = data.sumTo(data.end()) + queue.totalSize() + // doesn't account for overhead in queue
transactionSize;
return memoryLimit - residentSize;
}
StorageBytes getStorageBytes() const override {
StorageBytes diskQueueBytes = log->getStorageBytes();
// Try to bound how many in-memory bytes we might need to write to disk if we commit() now
int64_t uncommittedBytes = queue.totalSize() + transactionSize;
// Check that we have enough space in memory and on disk
int64_t freeSize = std::min(getAvailableSize(), diskQueueBytes.free / 4 - uncommittedBytes);
int64_t availableSize = std::min(getAvailableSize(), diskQueueBytes.available / 4 - uncommittedBytes);
int64_t totalSize = std::min(memoryLimit, diskQueueBytes.total / 4 - uncommittedBytes);
return StorageBytes(std::max((int64_t)0, freeSize),
std::max((int64_t)0, totalSize),
diskQueueBytes.used,
std::max((int64_t)0, availableSize));
}
void semiCommit() {
transactionSize += queue.totalSize();
if (transactionSize > 0.5 * committedDataSize) {
transactionIsLarge = true;
TraceEvent("KVSMemSwitchingToLargeTransactionMode", id)
.detail("TransactionSize", transactionSize)
.detail("DataSize", committedDataSize);
TEST(true); // KeyValueStoreMemory switching to large transaction mode
TEST(committedDataSize >
1e3); // KeyValueStoreMemory switching to large transaction mode with committed data
}
int64_t bytesWritten = commit_queue(queue, true);
committedWriteBytes += bytesWritten;
}
void set(KeyValueRef keyValue, const Arena* arena) override {
// A commit that occurs with no available space returns Never, so we can throw out all modifications
if (getAvailableSize() <= 0)
return;
if (transactionIsLarge) {
data.insert(keyValue.key, keyValue.value);
} else {
queue.set(keyValue, arena);
if (recovering.isReady() && !disableSnapshot) {
semiCommit();
}
}
}
void clear(KeyRangeRef range, const Arena* arena) override {
// A commit that occurs with no available space returns Never, so we can throw out all modifications
if (getAvailableSize() <= 0)
return;
if (transactionIsLarge) {
data.erase(data.lower_bound(range.begin), data.lower_bound(range.end));
} else {
queue.clear(range, arena);
if (recovering.isReady() && !disableSnapshot) {
semiCommit();
}
}
}
Future<Void> commit(bool sequential) override {
if (getAvailableSize() <= 0) {
TraceEvent(SevError, "KeyValueStoreMemory_OutOfSpace", id).log();
return Never();
}
if (recovering.isError())
throw recovering.getError();
if (!recovering.isReady())
return waitAndCommit(this, sequential);
if (!disableSnapshot && replaceContent && !firstCommitWithSnapshot) {
transactionSize += SERVER_KNOBS->REPLACE_CONTENTS_BYTES;
committedWriteBytes += SERVER_KNOBS->REPLACE_CONTENTS_BYTES;
semiCommit();
}
if (transactionIsLarge) {
fullSnapshot(data);
resetSnapshot = true;
committedWriteBytes = notifiedCommittedWriteBytes.get();
overheadWriteBytes = 0;
if (disableSnapshot) {
return Void();
}
log_op(OpCommit, StringRef(), StringRef());
} else {
int64_t bytesWritten = commit_queue(queue, !disableSnapshot, sequential);
if (disableSnapshot) {
return Void();
}
if (bytesWritten > 0 || committedWriteBytes > notifiedCommittedWriteBytes.get()) {
committedWriteBytes += bytesWritten + overheadWriteBytes +
OP_DISK_OVERHEAD; // OP_DISK_OVERHEAD is for the following log_op(OpCommit)
notifiedCommittedWriteBytes.set(committedWriteBytes); // This set will cause snapshot items to be
// written, so it must happen before the OpCommit
log_op(OpCommit, StringRef(), StringRef());
overheadWriteBytes = log->getCommitOverhead();
}
}
auto c = log->commit();
committedDataSize = data.sumTo(data.end());
transactionSize = 0;
transactionIsLarge = false;
firstCommitWithSnapshot = false;
addActor.send(commitAndUpdateVersions(this, c, previousSnapshotEnd));
return c;
}
Future<Optional<Value>> readValue(KeyRef key, IKeyValueStore::ReadType, Optional<UID> debugID) override {
if (recovering.isError())
throw recovering.getError();
if (!recovering.isReady())
return waitAndReadValue(this, key);
auto it = data.find(key);
if (it == data.end())
return Optional<Value>();
return Optional<Value>(it.getValue());
}
Future<Optional<Value>> readValuePrefix(KeyRef key,
int maxLength,
IKeyValueStore::ReadType,
Optional<UID> debugID) override {
if (recovering.isError())
throw recovering.getError();
if (!recovering.isReady())
return waitAndReadValuePrefix(this, key, maxLength);
auto it = data.find(key);
if (it == data.end())
return Optional<Value>();
auto val = it.getValue();
if (maxLength < val.size()) {
return Optional<Value>(val.substr(0, maxLength));
} else {
return Optional<Value>(val);
}
}
// If rowLimit>=0, reads first rows sorted ascending, otherwise reads last rows sorted descending
// The total size of the returned value (less the last entry) will be less than byteLimit
Future<RangeResult> readRange(KeyRangeRef keys, int rowLimit, int byteLimit, IKeyValueStore::ReadType) override {
if (recovering.isError())
throw recovering.getError();
if (!recovering.isReady())
return waitAndReadRange(this, keys, rowLimit, byteLimit);
RangeResult result;
if (rowLimit == 0) {
return result;
}
if (rowLimit > 0) {
auto it = data.lower_bound(keys.begin);
while (it != data.end() && rowLimit && byteLimit > 0) {
StringRef tempKey = it.getKey(reserved_buffer);
if (tempKey >= keys.end)
break;
byteLimit -= sizeof(KeyValueRef) + tempKey.size() + it.getValue().size();
result.push_back_deep(result.arena(), KeyValueRef(tempKey, it.getValue()));
++it;
--rowLimit;
}
} else {
rowLimit = -rowLimit;
auto it = data.previous(data.lower_bound(keys.end));
while (it != data.end() && rowLimit && byteLimit > 0) {
StringRef tempKey = it.getKey(reserved_buffer);
if (tempKey < keys.begin)
break;
byteLimit -= sizeof(KeyValueRef) + tempKey.size() + it.getValue().size();
result.push_back_deep(result.arena(), KeyValueRef(tempKey, it.getValue()));
it = data.previous(it);
--rowLimit;
}
}
result.more = rowLimit == 0 || byteLimit <= 0;
if (result.more) {
ASSERT(result.size() > 0);
result.readThrough = result[result.size() - 1].key;
}
return result;
}
void resyncLog() override {
ASSERT(recovering.isReady());
resetSnapshot = true;
log_op(OpSnapshotAbort, StringRef(), StringRef());
}
void enableSnapshot() override { disableSnapshot = false; }
private:
enum OpType {
OpSet,
OpClear,
OpClearToEnd,
OpSnapshotItem,
OpSnapshotEnd,
OpSnapshotAbort, // terminate an in progress snapshot in order to start a full snapshot
OpCommit, // only in log, not in queue
OpRollback, // only in log, not in queue
OpSnapshotItemDelta
};
struct OpRef {
OpType op;
StringRef p1, p2;
OpRef() {}
OpRef(Arena& a, OpRef const& o) : op(o.op), p1(a, o.p1), p2(a, o.p2) {}
size_t expectedSize() const { return p1.expectedSize() + p2.expectedSize(); }
};
struct OpHeader {
int op;
int len1, len2;
};
struct OpQueue {
OpQueue() : numBytes(0) {}
int totalSize() const { return numBytes; }
void clear() {
numBytes = 0;
operations = Standalone<VectorRef<OpRef>>();
arenas.clear();
}
void rollback() { clear(); }
void set(KeyValueRef keyValue, const Arena* arena = nullptr) {
queue_op(OpSet, keyValue.key, keyValue.value, arena);
}
void clear(KeyRangeRef range, const Arena* arena = nullptr) {
queue_op(OpClear, range.begin, range.end, arena);
}
void clear_to_end(StringRef fromKey, const Arena* arena = nullptr) {
queue_op(OpClearToEnd, fromKey, StringRef(), arena);
}
void queue_op(OpType op, StringRef p1, StringRef p2, const Arena* arena) {
numBytes += p1.size() + p2.size() + sizeof(OpHeader) + sizeof(OpRef);
OpRef r;
r.op = op;
r.p1 = p1;
r.p2 = p2;
if (arena == nullptr) {
operations.push_back_deep(operations.arena(), r);
} else {
operations.push_back(operations.arena(), r);
arenas.push_back(*arena);
}
}
const OpRef* begin() { return operations.begin(); }
const OpRef* end() { return operations.end(); }
private:
Standalone<VectorRef<OpRef>> operations;
uint64_t numBytes;
std::vector<Arena> arenas;
};
KeyValueStoreType type;
UID id;
Container data;
// reserved buffer for snapshot/fullsnapshot
uint8_t* reserved_buffer;
OpQueue queue; // mutations not yet commit()ted
IDiskQueue* log;
Future<Void> recovering, snapshotting;
int64_t committedWriteBytes;
int64_t overheadWriteBytes;
NotifiedVersion notifiedCommittedWriteBytes;
Key recoveredSnapshotKey; // After recovery, the next key in the currently uncompleted snapshot
IDiskQueue::location
currentSnapshotEnd; // The end of the most recently completed snapshot (this snapshot cannot be discarded)
IDiskQueue::location previousSnapshotEnd; // The end of the second most recently completed snapshot (on commit, this
// snapshot can be discarded)
PromiseStream<Future<Void>> addActor;
Future<Void> commitActors;
int64_t committedDataSize;
int64_t transactionSize;
bool transactionIsLarge;
bool resetSnapshot; // Set to true after a fullSnapshot is performed. This causes the regular snapshot mechanism to
// restart
bool disableSnapshot;
bool replaceContent;
bool firstCommitWithSnapshot;
int snapshotCount;
int64_t memoryLimit; // The upper limit on the memory used by the store (excluding, possibly, some clear operations)
std::vector<std::pair<KeyValueMapPair, uint64_t>> dataSets;
int64_t commit_queue(OpQueue& ops, bool log, bool sequential = false) {
int64_t total = 0, count = 0;
IDiskQueue::location log_location = 0;
for (auto o = ops.begin(); o != ops.end(); ++o) {
++count;
total += o->p1.size() + o->p2.size() + OP_DISK_OVERHEAD;
if (o->op == OpSet) {
if (sequential) {
KeyValueMapPair pair(o->p1, o->p2);
dataSets.emplace_back(pair, pair.arena.getSize() + data.getElementBytes());
} else {
data.insert(o->p1, o->p2);
}
} else if (o->op == OpClear) {
if (sequential) {
data.insert(dataSets);
dataSets.clear();
}
data.erase(data.lower_bound(o->p1), data.lower_bound(o->p2));
} else if (o->op == OpClearToEnd) {
if (sequential) {
data.insert(dataSets);
dataSets.clear();
}
data.erase(data.lower_bound(o->p1), data.end());
} else
ASSERT(false);
if (log)
log_location = log_op(o->op, o->p1, o->p2);
}
if (sequential) {
data.insert(dataSets);
dataSets.clear();
}
bool ok = count < 1e6;
if (!ok) {
TraceEvent(/*ok ? SevInfo : */ SevWarnAlways, "KVSMemCommitQueue", id)
.detail("Bytes", total)
.detail("Log", log)
.detail("Ops", count)
.detail("LastLoggedLocation", log_location)
.detail("Details", count);
}
ops.clear();
return total;
}
IDiskQueue::location log_op(OpType op, StringRef v1, StringRef v2) {
OpHeader h = { (int)op, v1.size(), v2.size() };
log->push(StringRef((const uint8_t*)&h, sizeof(h)));
log->push(v1);
log->push(v2);
return log->push(LiteralStringRef("\x01")); // Changes here should be reflected in OP_DISK_OVERHEAD
}
ACTOR static Future<Void> recover(KeyValueStoreMemory* self, bool exactRecovery) {
loop {
// 'uncommitted' variables track something that might be rolled back by an OpRollback, and are copied into
// permanent variables (in self) in OpCommit. OpRollback does the reverse (copying the permanent versions
// over the uncommitted versions) the uncommitted and committed variables should be equal initially (to
// whatever makes sense if there are no committed transactions recovered)
state Key uncommittedNextKey = self->recoveredSnapshotKey;
state IDiskQueue::location uncommittedPrevSnapshotEnd = self->previousSnapshotEnd =
self->log->getNextReadLocation(); // not really, but popping up to here does nothing
state IDiskQueue::location uncommittedSnapshotEnd = self->currentSnapshotEnd = uncommittedPrevSnapshotEnd;
state int zeroFillSize = 0;
state int dbgSnapshotItemCount = 0;
state int dbgSnapshotEndCount = 0;
state int dbgMutationCount = 0;
state int dbgCommitCount = 0;
state double startt = now();
state UID dbgid = self->id;
state Future<Void> loggingDelay = delay(1.0);
state OpQueue recoveryQueue;
state OpHeader h;
state Standalone<StringRef> lastSnapshotKey;
TraceEvent("KVSMemRecoveryStarted", self->id).detail("SnapshotEndLocation", uncommittedSnapshotEnd);
try {
loop {
{
Standalone<StringRef> data = wait(self->log->readNext(sizeof(OpHeader)));
if (data.size() != sizeof(OpHeader)) {
if (data.size()) {
TEST(true); // zero fill partial header in KeyValueStoreMemory
memset(&h, 0, sizeof(OpHeader));
memcpy(&h, data.begin(), data.size());
zeroFillSize = sizeof(OpHeader) - data.size() + h.len1 + h.len2 + 1;
}
TraceEvent("KVSMemRecoveryComplete", self->id)
.detail("Reason", "Non-header sized data read")
.detail("DataSize", data.size())
.detail("ZeroFillSize", zeroFillSize)
.detail("SnapshotEndLocation", uncommittedSnapshotEnd)
.detail("NextReadLoc", self->log->getNextReadLocation());
break;
}
h = *(OpHeader*)data.begin();
}
Standalone<StringRef> data = wait(self->log->readNext(h.len1 + h.len2 + 1));
if (data.size() != h.len1 + h.len2 + 1) {
zeroFillSize = h.len1 + h.len2 + 1 - data.size();
TraceEvent("KVSMemRecoveryComplete", self->id)
.detail("Reason", "data specified by header does not exist")
.detail("DataSize", data.size())
.detail("ZeroFillSize", zeroFillSize)
.detail("SnapshotEndLocation", uncommittedSnapshotEnd)
.detail("OpCode", h.op)
.detail("NextReadLoc", self->log->getNextReadLocation());
break;
}
if (data[data.size() - 1]) {
StringRef p1 = data.substr(0, h.len1);
StringRef p2 = data.substr(h.len1, h.len2);
if (h.op == OpSnapshotItem || h.op == OpSnapshotItemDelta) { // snapshot data item
/*if (p1 < uncommittedNextKey) {
TraceEvent(SevError, "RecSnapshotBack", self->id)
.detail("NextKey", uncommittedNextKey)
.detail("P1", p1)
.detail("Nextlocation", self->log->getNextReadLocation());
}
ASSERT( p1 >= uncommittedNextKey );*/
if (h.op == OpSnapshotItemDelta) {
ASSERT(p1.size() > 1);
// Get number of bytes borrowed from previous item key
int borrowed = *(uint8_t*)p1.begin();
ASSERT(borrowed <= lastSnapshotKey.size());
// Trim p1 to just the suffix
StringRef suffix = p1.substr(1);
// Allocate a new string in data arena to hold prefix + suffix
Arena& dataArena = *(Arena*)&data.arena();
p1 = makeString(borrowed + suffix.size(), dataArena);
// Copy the prefix into the new reconstituted key
memcpy(mutateString(p1), lastSnapshotKey.begin(), borrowed);
// Copy the suffix into the new reconstituted key
memcpy(mutateString(p1) + borrowed, suffix.begin(), suffix.size());
}
if (p1 >= uncommittedNextKey)
recoveryQueue.clear(
KeyRangeRef(uncommittedNextKey, p1),
&uncommittedNextKey
.arena()); // FIXME: Not sure what this line is for, is it necessary?
recoveryQueue.set(KeyValueRef(p1, p2), &data.arena());
uncommittedNextKey = keyAfter(p1);
++dbgSnapshotItemCount;
lastSnapshotKey = Key(p1, data.arena());
} else if (h.op == OpSnapshotEnd || h.op == OpSnapshotAbort) { // snapshot complete
TraceEvent("RecSnapshotEnd", self->id)
.detail("NextKey", uncommittedNextKey)
.detail("Nextlocation", self->log->getNextReadLocation())
.detail("IsSnapshotEnd", h.op == OpSnapshotEnd);
if (h.op == OpSnapshotEnd) {
uncommittedPrevSnapshotEnd = uncommittedSnapshotEnd;
uncommittedSnapshotEnd = self->log->getNextReadLocation();
recoveryQueue.clear_to_end(uncommittedNextKey, &uncommittedNextKey.arena());
}
uncommittedNextKey = Key();
lastSnapshotKey = Key();
++dbgSnapshotEndCount;
} else if (h.op == OpSet) { // set mutation
recoveryQueue.set(KeyValueRef(p1, p2), &data.arena());
++dbgMutationCount;
} else if (h.op == OpClear) { // clear mutation
recoveryQueue.clear(KeyRangeRef(p1, p2), &data.arena());
++dbgMutationCount;
} else if (h.op == OpClearToEnd) { // clear all data from begin key to end
recoveryQueue.clear_to_end(p1, &data.arena());
} else if (h.op == OpCommit) { // commit previous transaction
self->commit_queue(recoveryQueue, false);
++dbgCommitCount;
self->recoveredSnapshotKey = uncommittedNextKey;
self->previousSnapshotEnd = uncommittedPrevSnapshotEnd;
self->currentSnapshotEnd = uncommittedSnapshotEnd;
} else if (h.op == OpRollback) { // rollback previous transaction
recoveryQueue.rollback();
TraceEvent("KVSMemRecSnapshotRollback", self->id).detail("NextKey", uncommittedNextKey);
uncommittedNextKey = self->recoveredSnapshotKey;
uncommittedPrevSnapshotEnd = self->previousSnapshotEnd;
uncommittedSnapshotEnd = self->currentSnapshotEnd;
} else
ASSERT(false);
} else {
TraceEvent("KVSMemRecoverySkippedZeroFill", self->id)
.detail("PayloadSize", data.size())
.detail("ExpectedSize", h.len1 + h.len2 + 1)
.detail("OpCode", h.op)
.detail("EndsAt", self->log->getNextReadLocation());
}
if (loggingDelay.isReady()) {
TraceEvent("KVSMemRecoveryLogSnap", self->id)
.detail("SnapshotItems", dbgSnapshotItemCount)
.detail("SnapshotEnd", dbgSnapshotEndCount)
.detail("Mutations", dbgMutationCount)
.detail("Commits", dbgCommitCount)
.detail("EndsAt", self->log->getNextReadLocation());
loggingDelay = delay(1.0);
}
wait(yield());
}
if (zeroFillSize) {
if (exactRecovery) {
TraceEvent(SevError, "KVSMemExpectedExact", self->id).log();
ASSERT(false);
}
TEST(true); // Fixing a partial commit at the end of the KeyValueStoreMemory log
for (int i = 0; i < zeroFillSize; i++)
self->log->push(StringRef((const uint8_t*)"", 1));
}
// self->rollback(); not needed, since we are about to discard anything left in the recoveryQueue
//TraceEvent("KVSMemRecRollback", self->id).detail("QueueEmpty", data.size() == 0);
// make sure that before any new operations are added to the log that all uncommitted operations are
// "rolled back"
self->log_op(OpRollback, StringRef(), StringRef()); // rollback previous transaction
self->committedDataSize = self->data.sumTo(self->data.end());
TraceEvent("KVSMemRecovered", self->id)
.detail("SnapshotItems", dbgSnapshotItemCount)
.detail("SnapshotEnd", dbgSnapshotEndCount)
.detail("Mutations", dbgMutationCount)
.detail("Commits", dbgCommitCount)
.detail("TimeTaken", now() - startt);
self->semiCommit();
return Void();
} catch (Error& e) {
bool ok = e.code() == error_code_operation_cancelled || e.code() == error_code_file_not_found ||
e.code() == error_code_disk_adapter_reset;
TraceEvent(ok ? SevInfo : SevError, "ErrorDuringRecovery", dbgid).errorUnsuppressed(e);
if (e.code() != error_code_disk_adapter_reset) {
throw e;
}
self->data.clear();
self->dataSets.clear();
}
}
}
// Snapshots an entire data set
void fullSnapshot(Container& snapshotData) {
previousSnapshotEnd = log_op(OpSnapshotAbort, StringRef(), StringRef());
replaceContent = false;
// Clear everything since we are about to write the whole database
log_op(OpClearToEnd, allKeys.begin, StringRef());
int count = 0;
int64_t snapshotSize = 0;
for (auto kv = snapshotData.begin(); kv != snapshotData.end(); ++kv) {
StringRef tempKey = kv.getKey(reserved_buffer);
log_op(OpSnapshotItem, tempKey, kv.getValue());
snapshotSize += tempKey.size() + kv.getValue().size() + OP_DISK_OVERHEAD;
++count;
}
TraceEvent("FullSnapshotEnd", id)
.detail("PreviousSnapshotEndLoc", previousSnapshotEnd)
.detail("SnapshotSize", snapshotSize)
.detail("SnapshotElements", count);
currentSnapshotEnd = log_op(OpSnapshotEnd, StringRef(), StringRef());
}
ACTOR static Future<Void> snapshot(KeyValueStoreMemory* self) {
wait(self->recovering);
state Key nextKey = self->recoveredSnapshotKey;
state bool nextKeyAfter = false; // setting this to true is equilvent to setting nextKey = keyAfter(nextKey)
state uint64_t snapshotTotalWrittenBytes = 0;
state int lastDiff = 0;
state int snapItems = 0;
state uint64_t snapshotBytes = 0;
// Snapshot keys will be alternately written to two preallocated buffers.
// This allows consecutive snapshot keys to be compared for delta compression while only copying each key's
// bytes once.
state Key lastSnapshotKeyA = makeString(CLIENT_KNOBS->SYSTEM_KEY_SIZE_LIMIT);
state Key lastSnapshotKeyB = makeString(CLIENT_KNOBS->SYSTEM_KEY_SIZE_LIMIT);
state bool lastSnapshotKeyUsingA = true;
TraceEvent("KVSMemStartingSnapshot", self->id).detail("StartKey", nextKey);
loop {
wait(self->notifiedCommittedWriteBytes.whenAtLeast(snapshotTotalWrittenBytes + 1));
if (self->resetSnapshot) {
nextKey = Key();
nextKeyAfter = false;
snapItems = 0;
snapshotBytes = 0;
self->resetSnapshot = false;
}
auto next = nextKeyAfter ? self->data.upper_bound(nextKey) : self->data.lower_bound(nextKey);
int diff = self->notifiedCommittedWriteBytes.get() - snapshotTotalWrittenBytes;
if (diff > lastDiff && diff > 5e7)
TraceEvent(SevWarnAlways, "ManyWritesAtOnce", self->id)
.detail("CommittedWrites", self->notifiedCommittedWriteBytes.get())
.detail("SnapshotWrites", snapshotTotalWrittenBytes)
.detail("Diff", diff)
.detail("LastOperationWasASnapshot", nextKey == Key() && !nextKeyAfter);
lastDiff = diff;
// Since notifiedCommittedWriteBytes is only set() once per commit, before logging the commit operation,
// when this line is reached it is certain that there are no snapshot items in this commit yet. Since this
// commit could be the first thing read during recovery, we can't write a delta yet.
bool useDelta = false;
// Write snapshot items until the wait above would block because we've used up all of the byte budget
loop {
if (next == self->data.end()) {
// After a snapshot end is logged, recovery may not see the last snapshot item logged before it so
// the next snapshot item logged cannot be a delta.
useDelta = false;
auto thisSnapshotEnd = self->log_op(OpSnapshotEnd, StringRef(), StringRef());
//TraceEvent("SnapshotEnd", self->id)
// .detail("LastKey", lastKey.present() ? lastKey.get() : LiteralStringRef("<none>"))
// .detail("CurrentSnapshotEndLoc", self->currentSnapshotEnd)
// .detail("PreviousSnapshotEndLoc", self->previousSnapshotEnd)
// .detail("ThisSnapshotEnd", thisSnapshotEnd)
// .detail("Items", snapItems)
// .detail("CommittedWrites", self->notifiedCommittedWriteBytes.get())
// .detail("SnapshotSize", snapshotBytes);
ASSERT(thisSnapshotEnd >= self->currentSnapshotEnd);
self->previousSnapshotEnd = self->currentSnapshotEnd;
self->currentSnapshotEnd = thisSnapshotEnd;
if (++self->snapshotCount == 2) {
self->replaceContent = false;
}
snapItems = 0;
snapshotBytes = 0;
snapshotTotalWrittenBytes += OP_DISK_OVERHEAD;
// If we're not stopping now, reset next
if (snapshotTotalWrittenBytes < self->notifiedCommittedWriteBytes.get()) {
next = self->data.begin();
} else {
// Otherwise, save state for continuing after the next wait and stop
nextKey = Key();
nextKeyAfter = false;
break;
}
} else {
// destKey is whichever of the two last key buffers we should write to next.
Key& destKey = lastSnapshotKeyUsingA ? lastSnapshotKeyA : lastSnapshotKeyB;
// Get the key, using destKey as a temporary buffer if needed.
KeyRef tempKey = next.getKey(mutateString(destKey));
int opKeySize = tempKey.size();
// If tempKey did not use the start of destKey, then copy tempKey into destKey.
// It's technically possible for the source and dest to overlap but with the current container
// implementations that will not happen.
if (tempKey.begin() != destKey.begin()) {
memcpy(mutateString(destKey), tempKey.begin(), tempKey.size());
}
// Now, tempKey's bytes definitely exist in memory at destKey.begin() so update destKey's contents
// to be a proper KeyRef of the key. This intentionally leaves the Arena alone and doesn't copy
// anything into it.
destKey.contents() = KeyRef(destKey.begin(), tempKey.size());
// Get the common prefix between this key and the previous one, or 0 if there was no previous one.
int commonPrefix;
if (useDelta && SERVER_KNOBS->PREFIX_COMPRESS_KVS_MEM_SNAPSHOTS) {
commonPrefix = commonPrefixLength(lastSnapshotKeyA, lastSnapshotKeyB);
} else {
commonPrefix = 0;
useDelta = true;
}
// If the common prefix is greater than 1, write a delta item. It isn't worth doing for 0 or 1
// bytes, it would merely add decode overhead (string copying).
if (commonPrefix > 1) {
// Cap the common prefix length to 255. Sorry, ridiculously long keys!
commonPrefix = std::min<int>(commonPrefix, std::numeric_limits<uint8_t>::max());
// We're going to temporarily write a 1-byte integer just before the key suffix to create the
// log op key and log it, then restore that byte.
uint8_t& prefixLength = mutateString(destKey)[commonPrefix - 1];
uint8_t backupByte = prefixLength;
prefixLength = commonPrefix;
opKeySize = opKeySize - commonPrefix + 1;
KeyRef opKey(&prefixLength, opKeySize);
self->log_op(OpSnapshotItemDelta, opKey, next.getValue());
// Restore the overwritten byte
prefixLength = backupByte;
} else {
self->log_op(OpSnapshotItem, tempKey, next.getValue());
}
snapItems++;
uint64_t opBytes = opKeySize + next.getValue().size() + OP_DISK_OVERHEAD;
snapshotBytes += opBytes;
snapshotTotalWrittenBytes += opBytes;
lastSnapshotKeyUsingA = !lastSnapshotKeyUsingA;
// If we're not stopping now, increment next
if (snapshotTotalWrittenBytes < self->notifiedCommittedWriteBytes.get()) {
++next;
} else {
// Otherwise, save state for continuing after the next wait and stop
nextKey = destKey;
nextKeyAfter = true;
break;
}
}
}
}
}
ACTOR static Future<Optional<Value>> waitAndReadValue(KeyValueStoreMemory* self, Key key) {
wait(self->recovering);
return static_cast<IKeyValueStore*>(self)->readValue(key).get();
}
ACTOR static Future<Optional<Value>> waitAndReadValuePrefix(KeyValueStoreMemory* self, Key key, int maxLength) {
wait(self->recovering);
return static_cast<IKeyValueStore*>(self)->readValuePrefix(key, maxLength).get();
}
ACTOR static Future<RangeResult> waitAndReadRange(KeyValueStoreMemory* self,
KeyRange keys,
int rowLimit,
int byteLimit) {
wait(self->recovering);
return static_cast<IKeyValueStore*>(self)->readRange(keys, rowLimit, byteLimit).get();
}
ACTOR static Future<Void> waitAndCommit(KeyValueStoreMemory* self, bool sequential) {
wait(self->recovering);
wait(self->commit(sequential));
return Void();
}
ACTOR static Future<Void> commitAndUpdateVersions(KeyValueStoreMemory* self,
Future<Void> commit,
IDiskQueue::location location) {
wait(commit);
self->log->pop(location);
return Void();
}
};
template <typename Container>
KeyValueStoreMemory<Container>::KeyValueStoreMemory(IDiskQueue* log,
UID id,
int64_t memoryLimit,
KeyValueStoreType storeType,
bool disableSnapshot,
bool replaceContent,
bool exactRecovery)
: type(storeType), id(id), log(log), committedWriteBytes(0), overheadWriteBytes(0), currentSnapshotEnd(-1),
previousSnapshotEnd(-1), committedDataSize(0), transactionSize(0), transactionIsLarge(false), resetSnapshot(false),
disableSnapshot(disableSnapshot), replaceContent(replaceContent), firstCommitWithSnapshot(true), snapshotCount(0),
memoryLimit(memoryLimit) {
// create reserved buffer for radixtree store type
this->reserved_buffer =
(storeType == KeyValueStoreType::MEMORY) ? nullptr : new uint8_t[CLIENT_KNOBS->SYSTEM_KEY_SIZE_LIMIT];
if (this->reserved_buffer != nullptr)
memset(this->reserved_buffer, 0, CLIENT_KNOBS->SYSTEM_KEY_SIZE_LIMIT);
recovering = recover(this, exactRecovery);
snapshotting = snapshot(this);
commitActors = actorCollection(addActor.getFuture());
}
IKeyValueStore* keyValueStoreMemory(std::string const& basename,
UID logID,
int64_t memoryLimit,
std::string ext,
KeyValueStoreType storeType) {
TraceEvent("KVSMemOpening", logID)
.detail("Basename", basename)
.detail("MemoryLimit", memoryLimit)
.detail("StoreType", storeType);
// SOMEDAY: update to use DiskQueueVersion::V2 with xxhash3 checksum for FDB >= 7.2
IDiskQueue* log = openDiskQueue(basename, ext, logID, DiskQueueVersion::V1);
if (storeType == KeyValueStoreType::MEMORY_RADIXTREE) {
return new KeyValueStoreMemory<radix_tree>(log, logID, memoryLimit, storeType, false, false, false);
} else {
return new KeyValueStoreMemory<IKeyValueContainer>(log, logID, memoryLimit, storeType, false, false, false);
}
}
IKeyValueStore* keyValueStoreLogSystem(class IDiskQueue* queue,
UID logID,
int64_t memoryLimit,
bool disableSnapshot,
bool replaceContent,
bool exactRecovery) {
return new KeyValueStoreMemory<IKeyValueContainer>(
queue, logID, memoryLimit, KeyValueStoreType::MEMORY, disableSnapshot, replaceContent, exactRecovery);
}
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