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foundationdb/fdbclient/TagThrottle.actor.cpp

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/*
* TagThrottle.actor.cpp
*
* This source file is part of the FoundationDB open source project
*
* Copyright 2013-2020 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/TagThrottle.h"
#include "fdbclient/MasterProxyInterface.h"
#include "fdbclient/DatabaseContext.h"
#include "flow/actorcompiler.h" // has to be last include
void TagSet::addTag(TransactionTagRef tag) {
ASSERT(CLIENT_KNOBS->MAX_TRANSACTION_TAG_LENGTH < 256); // Tag length is encoded with a single byte
ASSERT(CLIENT_KNOBS->MAX_TAGS_PER_TRANSACTION < 256); // Number of tags is encoded with a single byte
if(tag.size() > CLIENT_KNOBS->MAX_TRANSACTION_TAG_LENGTH) {
throw tag_too_long();
}
if(tags.size() >= CLIENT_KNOBS->MAX_TAGS_PER_TRANSACTION) {
throw too_many_tags();
}
auto result = tags.insert(TransactionTagRef(arena, tag));
if(result.second) {
bytes += tag.size();
}
}
size_t TagSet::size() const {
return tags.size();
}
// Format for throttle key:
//
// tagThrottleKeysPrefix + [auto-throttled (1-byte 0/1)] + [priority (1-byte)] + [tag list]
// tag list consists of 1 or more consecutive tags, each encoded as:
// tag.size() (1 byte) + tag's bytes. For example, tag 'foo' is: \x03foo
// The tags are listed in sorted order
//
// Currently, the throttle API supports only 1 tag per throttle
Key TagThrottleKey::toKey() const {
ASSERT(CLIENT_KNOBS->MAX_TRANSACTION_TAG_LENGTH < 256);
ASSERT(tags.size() > 0);
ASSERT(tags.size() == 1); // SOMEDAY: support multiple tags per throttle
int size = tagThrottleKeysPrefix.size() + tags.size() + 2;
for(auto tag : tags) {
ASSERT(tag.size() <= CLIENT_KNOBS->MAX_TRANSACTION_TAG_LENGTH);
size += tag.size();
}
Key result;
uint8_t* str = new (result.arena()) uint8_t[size];
result.contents() = StringRef(str, size);
memcpy(str, tagThrottleKeysPrefix.begin(), tagThrottleKeysPrefix.size());
str += tagThrottleKeysPrefix.size();
*(str++) = (uint8_t)throttleType;
*(str++) = (uint8_t)priority;
for(auto tag : tags) {
*(str++) = (uint8_t)tag.size();
if(tag.size() > 0) {
memcpy(str, tag.begin(), tag.size());
str += tag.size();
}
}
return result;
}
TagThrottleKey TagThrottleKey::fromKey(const KeyRef& key) {
const uint8_t *str = key.substr(tagThrottleKeysPrefix.size()).begin();
TagThrottleType throttleType = TagThrottleType(*(str++));
TransactionPriority priority = TransactionPriority(*(str++));
TagSet tags;
while(str < key.end()) {
uint8_t size = *(str++);
tags.addTag(TransactionTagRef(str, size));
str += size;
}
return TagThrottleKey(tags, throttleType, priority);
}
TagThrottleValue TagThrottleValue::fromValue(const ValueRef& value) {
TagThrottleValue throttleValue;
BinaryReader reader(value, IncludeVersion());
reader >> throttleValue;
return throttleValue;
}
namespace ThrottleApi {
void signalThrottleChange(Transaction &tr) {
tr.atomicOp(tagThrottleSignalKey, LiteralStringRef("XXXXXXXXXX\x00\x00\x00\x00"), MutationRef::SetVersionstampedValue);
}
ACTOR Future<Void> updateThrottleCount(Transaction *tr, int64_t delta) {
state Future<Optional<Value>> countVal = tr->get(tagThrottleCountKey);
state Future<Optional<Value>> limitVal = tr->get(tagThrottleLimitKey);
wait(success(countVal) && success(limitVal));
int64_t count = 0;
int64_t limit = 0;
if(countVal.get().present()) {
BinaryReader reader(countVal.get().get(), Unversioned());
reader >> count;
}
if(limitVal.get().present()) {
BinaryReader reader(limitVal.get().get(), Unversioned());
reader >> limit;
}
count += delta;
if(count > limit) {
throw too_many_tag_throttles();
}
BinaryWriter writer(Unversioned());
writer << count;
tr->set(tagThrottleCountKey, writer.toValue());
return Void();
}
ACTOR Future<std::vector<TagThrottleInfo>> getThrottledTags(Database db, int limit) {
state Transaction tr(db);
loop {
try {
Standalone<RangeResultRef> throttles = wait(tr.getRange(tagThrottleKeys, limit));
std::vector<TagThrottleInfo> results;
for(auto throttle : throttles) {
results.push_back(TagThrottleInfo(TagThrottleKey::fromKey(throttle.key), TagThrottleValue::fromValue(throttle.value)));
}
return results;
}
catch(Error& e) {
wait(tr.onError(e));
}
}
}
ACTOR Future<Void> throttleTags(Database db, TagSet tags, double tpsRate, double initialDuration, TagThrottleType throttleType, TransactionPriority priority, Optional<double> expirationTime) {
state Transaction tr(db);
state Key key = TagThrottleKey(tags, throttleType, priority).toKey();
ASSERT(initialDuration > 0);
TagThrottleValue throttle(tpsRate, expirationTime.present() ? expirationTime.get() : 0, initialDuration);
BinaryWriter wr(IncludeVersion(ProtocolVersion::withTagThrottleValue()));
wr << throttle;
state Value value = wr.toValue();
loop {
try {
if(throttleType == TagThrottleType::MANUAL) {
Optional<Value> oldThrottle = wait(tr.get(key));
if(!oldThrottle.present()) {
wait(updateThrottleCount(&tr, 1));
}
}
tr.set(key, value);
if(throttleType == TagThrottleType::MANUAL) {
signalThrottleChange(tr);
}
wait(tr.commit());
return Void();
}
catch(Error& e) {
wait(tr.onError(e));
}
}
}
ACTOR Future<bool> unthrottleTags(Database db, TagSet tags, Optional<TagThrottleType> throttleType, Optional<TransactionPriority> priority) {
state Transaction tr(db);
state std::vector<Key> keys;
for(auto p : allTransactionPriorities) {
if(!priority.present() || priority.get() == p) {
if(!throttleType.present() || throttleType.get() == TagThrottleType::AUTO) {
keys.push_back(TagThrottleKey(tags, TagThrottleType::AUTO, p).toKey());
}
if(!throttleType.present() || throttleType.get() == TagThrottleType::MANUAL) {
keys.push_back(TagThrottleKey(tags, TagThrottleType::MANUAL, p).toKey());
}
}
}
state bool removed = false;
loop {
try {
state std::vector<Future<Optional<Value>>> values;
for(auto key : keys) {
values.push_back(tr.get(key));
}
wait(waitForAll(values));
int delta = 0;
for(int i = 0; i < values.size(); ++i) {
if(values[i].get().present()) {
if(TagThrottleKey::fromKey(keys[i]).throttleType == TagThrottleType::MANUAL) {
delta -= 1;
}
tr.clear(keys[i]);
// Report that we are removing this tag if we ever see it present.
// This protects us from getting confused if the transaction is maybe committed.
// It's ok if someone else actually ends up removing this tag at the same time
// and we aren't the ones to actually do it.
removed = true;
}
}
if(delta != 0) {
wait(updateThrottleCount(&tr, delta));
}
if(removed) {
signalThrottleChange(tr);
wait(tr.commit());
}
return removed;
}
catch(Error& e) {
wait(tr.onError(e));
}
}
}
ACTOR Future<bool> unthrottleMatchingThrottles(Database db, KeyRef beginKey, KeyRef endKey, Optional<TransactionPriority> priority, bool onlyExpiredThrottles) {
state Transaction tr(db);
state KeySelector begin = firstGreaterOrEqual(beginKey);
state KeySelector end = firstGreaterOrEqual(endKey);
state bool removed = false;
loop {
try {
state Standalone<RangeResultRef> tags = wait(tr.getRange(begin, end, 1000));
state uint64_t unthrottledTags = 0;
uint64_t manualUnthrottledTags = 0;
for(auto tag : tags) {
if(onlyExpiredThrottles) {
double expirationTime = TagThrottleValue::fromValue(tag.value).expirationTime;
if(expirationTime == 0 || expirationTime > now()) {
continue;
}
}
TagThrottleKey key = TagThrottleKey::fromKey(tag.key);
if(priority.present() && key.priority != priority.get()) {
continue;
}
if(key.throttleType == TagThrottleType::MANUAL) {
++manualUnthrottledTags;
}
removed = true;
tr.clear(tag.key);
}
if(manualUnthrottledTags > 0) {
wait(updateThrottleCount(&tr, -manualUnthrottledTags));
}
if(unthrottledTags > 0) {
signalThrottleChange(tr);
}
wait(tr.commit());
if(!tags.more) {
return removed;
}
ASSERT(tags.size() > 0);
begin = KeySelector(firstGreaterThan(tags[tags.size()-1].key), tags.arena());
}
catch(Error& e) {
wait(tr.onError(e));
}
}
}
Future<bool> unthrottleAll(Database db, Optional<TagThrottleType> tagThrottleType, Optional<TransactionPriority> priority) {
KeyRef begin = tagThrottleKeys.begin;
KeyRef end = tagThrottleKeys.end;
if(tagThrottleType.present() && tagThrottleType == TagThrottleType::AUTO) {
begin = tagThrottleAutoKeysPrefix;
}
else if(tagThrottleType.present() && tagThrottleType == TagThrottleType::MANUAL) {
end = tagThrottleAutoKeysPrefix;
}
return unthrottleMatchingThrottles(db, begin, end, priority, false);
}
Future<bool> expire(Database db) {
return unthrottleMatchingThrottles(db, tagThrottleKeys.begin, tagThrottleKeys.end, Optional<TransactionPriority>(), true);
}
ACTOR Future<Void> enableAuto(Database db, bool enabled) {
state Transaction tr(db);
loop {
try {
Optional<Value> value = wait(tr.get(tagThrottleAutoEnabledKey));
if(!value.present() || (enabled && value.get() != LiteralStringRef("1") || (!enabled && value.get() != LiteralStringRef("0")))) {
tr.set(tagThrottleAutoEnabledKey, LiteralStringRef(enabled ? "1" : "0"));
signalThrottleChange(tr);
wait(tr.commit());
}
return Void();
}
catch(Error& e) {
wait(tr.onError(e));
}
}
}
}
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