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series.go
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// Copyright (c) 2016 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package series
import (
"errors"
"fmt"
"sync"
"time"
"github.com/m3db/m3/src/dbnode/persist"
"github.com/m3db/m3/src/dbnode/storage/block"
"github.com/m3db/m3/src/dbnode/ts"
"github.com/m3db/m3/src/dbnode/x/xio"
"github.com/m3db/m3/src/m3ninx/doc"
"github.com/m3db/m3/src/x/context"
"github.com/m3db/m3/src/x/ident"
"github.com/m3db/m3/src/x/instrument"
xtime "github.com/m3db/m3/src/x/time"
"github.com/m3db/m3/src/dbnode/namespace"
"go.uber.org/zap"
)
var (
// ErrSeriesAllDatapointsExpired is returned on tick when all datapoints are expired
ErrSeriesAllDatapointsExpired = errors.New("series datapoints are all expired")
errSeriesAlreadyBootstrapped = errors.New("series is already bootstrapped")
errSeriesNotBootstrapped = errors.New("series is not yet bootstrapped")
errBlockStateSnapshotNotBootstrapped = errors.New("block state snapshot is not bootstrapped")
// Placeholder for a timeseries being bootstrapped which does not
// have access to the TS ID.
bootstrapWriteID = ident.StringID("bootstrap_timeseries")
)
type dbSeries struct {
sync.RWMutex
opts Options
// NB(r): One should audit all places that access the
// series metadata before changing ownership semantics (e.g.
// pooling the ID rather than releasing it to the GC on
// calling series.Reset()).
// Note: The bytes that back "id ident.ID" are the same bytes
// that are behind the ID in "metadata doc.Document", the whole
// reason we keep an ident.ID on the series is since there's a lot
// of existing callsites that require the ID as an ident.ID.
id ident.ID
metadata doc.Document
uniqueIndex uint64
bootstrap dbSeriesBootstrap
buffer databaseBuffer
cachedBlocks block.DatabaseSeriesBlocks
blockRetriever QueryableBlockRetriever
onRetrieveBlock block.OnRetrieveBlock
blockOnEvictedFromWiredList block.OnEvictedFromWiredList
pool DatabaseSeriesPool
}
type dbSeriesBootstrap struct {
sync.Mutex
// buffer should be nil unless this series
// has taken bootstrap writes.
buffer databaseBuffer
}
// NewDatabaseSeries creates a new database series.
func NewDatabaseSeries(opts DatabaseSeriesOptions) DatabaseSeries {
s := newDatabaseSeries()
s.Reset(opts)
return s
}
// newPooledDatabaseSeries creates a new pooled database series.
func newPooledDatabaseSeries(pool DatabaseSeriesPool) DatabaseSeries {
series := newDatabaseSeries()
series.pool = pool
return series
}
// NB(prateek): dbSeries.Reset(...) must be called upon the returned
// object prior to use.
func newDatabaseSeries() *dbSeries {
series := &dbSeries{
cachedBlocks: block.NewDatabaseSeriesBlocks(0),
}
series.buffer = newDatabaseBuffer()
return series
}
func (s *dbSeries) now() time.Time {
nowFn := s.opts.ClockOptions().NowFn()
return nowFn()
}
func (s *dbSeries) ID() ident.ID {
s.RLock()
id := s.id
s.RUnlock()
return id
}
func (s *dbSeries) Metadata() doc.Document {
s.RLock()
metadata := s.metadata
s.RUnlock()
return metadata
}
func (s *dbSeries) UniqueIndex() uint64 {
s.RLock()
uniqueIndex := s.uniqueIndex
s.RUnlock()
return uniqueIndex
}
func (s *dbSeries) Tick(blockStates ShardBlockStateSnapshot, nsCtx namespace.Context) (TickResult, error) {
var r TickResult
s.Lock()
bufferResult := s.buffer.Tick(blockStates, nsCtx)
r.MergedOutOfOrderBlocks = bufferResult.mergedOutOfOrderBlocks
r.EvictedBuckets = bufferResult.evictedBucketTimes.Len()
update, err := s.updateBlocksWithLock(blockStates, bufferResult.evictedBucketTimes)
if err != nil {
s.Unlock()
return r, err
}
r.TickStatus = update.TickStatus
r.MadeExpiredBlocks, r.MadeUnwiredBlocks =
update.madeExpiredBlocks, update.madeUnwiredBlocks
s.Unlock()
if update.ActiveBlocks > 0 {
return r, nil
}
// Check if any bootstrap writes that hasn't been merged yet.
s.bootstrap.Lock()
unmergedBootstrapDatapoints := s.bootstrap.buffer != nil
s.bootstrap.Unlock()
if unmergedBootstrapDatapoints {
return r, nil
}
// Everything expired.
return r, ErrSeriesAllDatapointsExpired
}
type updateBlocksResult struct {
TickStatus
madeExpiredBlocks int
madeUnwiredBlocks int
}
func (s *dbSeries) updateBlocksWithLock(
blockStates ShardBlockStateSnapshot,
evictedBucketTimes OptimizedTimes,
) (updateBlocksResult, error) {
var (
result updateBlocksResult
now = s.now()
ropts = s.opts.RetentionOptions()
cachePolicy = s.opts.CachePolicy()
expireCutoff = now.Add(-ropts.RetentionPeriod()).Truncate(ropts.BlockSize())
wiredTimeout = ropts.BlockDataExpiryAfterNotAccessedPeriod()
)
for startNano, currBlock := range s.cachedBlocks.AllBlocks() {
start := startNano.ToTime()
if start.Before(expireCutoff) || evictedBucketTimes.Contains(xtime.ToUnixNano(start)) {
s.cachedBlocks.RemoveBlockAt(start)
// If we're using the LRU policy and the block was retrieved from disk,
// then don't close the block because that is the WiredList's
// responsibility. The block will hang around the WiredList until
// it is evicted to make room for something else at which point it
// will be closed.
//
// Note that while we don't close the block, we do remove it from the list
// of blocks. This is so that the series itself can still be expired if this
// was the last block. The WiredList will still notify the shard/series via
// the OnEvictedFromWiredList method when it closes the block, but those
// methods are noops for series/blocks that have already been removed.
//
// Also note that while technically the DatabaseBlock protects against double
// closes, they can be problematic due to pooling. I.E if the following sequence
// of actions happens:
// 1) Tick closes expired block
// 2) Block is re-inserted into pool
// 3) Block is pulled out of pool and used for critical data
// 4) WiredList tries to close the block, not knowing that it has
// already been closed, and re-opened / re-used leading to
// unexpected behavior or data loss.
if cachePolicy == CacheLRU && currBlock.WasRetrievedFromDisk() {
// Do nothing
} else {
currBlock.Close()
}
result.madeExpiredBlocks++
continue
}
result.ActiveBlocks++
if cachePolicy == CacheAll {
// Never unwire
result.WiredBlocks++
continue
}
// Potentially unwire
var unwired, shouldUnwire bool
blockStatesSnapshot, bootstrapped := blockStates.UnwrapValue()
// Only use block state snapshot information to make eviction decisions if the block state
// has been properly bootstrapped already.
if bootstrapped {
// Makes sure that the block has been flushed, which
// prevents us from unwiring blocks that haven't been flushed yet which
// would cause data loss.
if blockState := blockStatesSnapshot.Snapshot[startNano]; blockState.WarmRetrievable {
switch cachePolicy {
case CacheNone:
shouldUnwire = true
case CacheRecentlyRead:
sinceLastRead := now.Sub(currBlock.LastReadTime())
shouldUnwire = sinceLastRead >= wiredTimeout
case CacheLRU:
// The tick is responsible for managing the lifecycle of blocks that were not
// read from disk (not retrieved), and the WiredList will manage those that were
// retrieved from disk.
shouldUnwire = !currBlock.WasRetrievedFromDisk()
default:
s.opts.InstrumentOptions().Logger().Fatal(
"unhandled cache policy in series tick", zap.Any("policy", cachePolicy))
}
}
}
if shouldUnwire {
// Remove the block and it will be looked up later
s.cachedBlocks.RemoveBlockAt(start)
currBlock.Close()
unwired = true
result.madeUnwiredBlocks++
}
if unwired {
result.UnwiredBlocks++
} else {
result.WiredBlocks++
if currBlock.HasMergeTarget() {
result.PendingMergeBlocks++
}
}
}
bufferStats := s.buffer.Stats()
result.ActiveBlocks += bufferStats.wiredBlocks
result.WiredBlocks += bufferStats.wiredBlocks
return result, nil
}
func (s *dbSeries) IsEmpty() bool {
s.RLock()
blocksLen := s.cachedBlocks.Len()
bufferEmpty := s.buffer.IsEmpty()
s.RUnlock()
if blocksLen == 0 && bufferEmpty {
return true
}
return false
}
func (s *dbSeries) IsBufferEmptyAtBlockStart(blockStart time.Time) bool {
s.RLock()
bufferEmpty := s.buffer.IsEmptyAtBlockStart(blockStart)
s.RUnlock()
return bufferEmpty
}
func (s *dbSeries) NumActiveBlocks() int {
s.RLock()
value := s.cachedBlocks.Len() + s.buffer.Stats().wiredBlocks
s.RUnlock()
return value
}
func (s *dbSeries) Write(
ctx context.Context,
timestamp time.Time,
value float64,
unit xtime.Unit,
annotation []byte,
wOpts WriteOptions,
) (bool, WriteType, error) {
if wOpts.BootstrapWrite {
// NB(r): If this is a bootstrap write we store this in a
// side buffer so that we don't need to take the series lock
// and contend with normal writes that are flowing into the DB
// while bootstrapping which can significantly interrupt
// write latency and cause entire DB to stall/degrade in performance.
return s.bootstrapWrite(ctx, timestamp, value, unit, annotation, wOpts)
}
s.Lock()
written, writeType, err := s.buffer.Write(ctx, s.id, timestamp, value,
unit, annotation, wOpts)
s.Unlock()
return written, writeType, err
}
func (s *dbSeries) bootstrapWrite(
ctx context.Context,
timestamp time.Time,
value float64,
unit xtime.Unit,
annotation []byte,
wOpts WriteOptions,
) (bool, WriteType, error) {
s.bootstrap.Lock()
defer s.bootstrap.Unlock()
if s.bootstrap.buffer == nil {
// Temporarily release bootstrap lock.
s.bootstrap.Unlock()
// Get reset opts.
resetOpts, err := s.bufferResetOpts()
// Re-lock bootstrap lock.
s.bootstrap.Lock()
if err != nil {
// Abort if failed to get buffer opts.
var writeType WriteType
return false, writeType, err
}
// If buffer still nil then set it.
if s.bootstrap.buffer == nil {
s.bootstrap.buffer = newDatabaseBuffer()
s.bootstrap.buffer.Reset(resetOpts)
}
}
return s.bootstrap.buffer.Write(ctx, bootstrapWriteID, timestamp,
value, unit, annotation, wOpts)
}
func (s *dbSeries) bufferResetOpts() (databaseBufferResetOptions, error) {
// Grab series lock.
s.RLock()
defer s.RUnlock()
if s.id == nil {
// Not active, expired series.
return databaseBufferResetOptions{}, ErrSeriesAllDatapointsExpired
}
return databaseBufferResetOptions{
BlockRetriever: s.blockRetriever,
Options: s.opts,
}, nil
}
func (s *dbSeries) ReadEncoded(
ctx context.Context,
start, end time.Time,
nsCtx namespace.Context,
) ([][]xio.BlockReader, error) {
s.RLock()
reader := NewReaderUsingRetriever(s.id, s.blockRetriever, s.onRetrieveBlock, s, s.opts)
r, err := reader.readersWithBlocksMapAndBuffer(ctx, start, end, s.cachedBlocks, s.buffer, nsCtx)
s.RUnlock()
return r, err
}
func (s *dbSeries) FetchBlocksForColdFlush(
ctx context.Context,
start time.Time,
version int,
nsCtx namespace.Context,
) (block.FetchBlockResult, error) {
// This needs a write lock because the version on underlying buckets need
// to be modified.
s.Lock()
result, err := s.buffer.FetchBlocksForColdFlush(ctx, start, version, nsCtx)
s.Unlock()
return result, err
}
func (s *dbSeries) FetchBlocks(
ctx context.Context,
starts []time.Time,
nsCtx namespace.Context,
) ([]block.FetchBlockResult, error) {
s.RLock()
r, err := Reader{
opts: s.opts,
id: s.id,
retriever: s.blockRetriever,
onRetrieve: s.onRetrieveBlock,
}.fetchBlocksWithBlocksMapAndBuffer(ctx, starts, s.cachedBlocks, s.buffer, nsCtx)
s.RUnlock()
return r, err
}
func (s *dbSeries) FetchBlocksMetadata(
ctx context.Context,
start, end time.Time,
opts FetchBlocksMetadataOptions,
) (block.FetchBlocksMetadataResult, error) {
s.RLock()
defer s.RUnlock()
res := s.opts.FetchBlockMetadataResultsPool().Get()
// Iterate over the encoders in the database buffer
if !s.buffer.IsEmpty() {
bufferResults, err := s.buffer.FetchBlocksMetadata(ctx, start, end, opts)
if err != nil {
return block.FetchBlocksMetadataResult{}, err
}
for _, result := range bufferResults.Results() {
res.Add(result)
}
bufferResults.Close()
}
res.Sort()
// NB(r): Since ID and Tags are garbage collected we can safely
// return refs.
tagsIter := s.opts.IdentifierPool().TagsIterator()
tagsIter.ResetFields(s.metadata.Fields)
return block.NewFetchBlocksMetadataResult(s.id, tagsIter, res), nil
}
func (s *dbSeries) addBlockWithLock(b block.DatabaseBlock) {
b.SetOnEvictedFromWiredList(s.blockOnEvictedFromWiredList)
s.cachedBlocks.AddBlock(b)
}
func (s *dbSeries) LoadBlock(
block block.DatabaseBlock,
writeType WriteType,
) error {
switch writeType {
case WarmWrite:
at := block.StartTime()
alreadyExists, err := s.blockRetriever.IsBlockRetrievable(at)
if err != nil {
err = fmt.Errorf("error checking warm block load valid: %v", err)
instrument.EmitAndLogInvariantViolation(s.opts.InstrumentOptions(),
func(l *zap.Logger) {
l.Error("warm load block invariant", zap.Error(err))
})
return err
}
if alreadyExists {
err = fmt.Errorf(
"warm block load for block that exists: block_start=%s", at)
instrument.EmitAndLogInvariantViolation(s.opts.InstrumentOptions(),
func(l *zap.Logger) {
l.Error("warm load block invariant", zap.Error(err))
})
return err
}
}
s.Lock()
s.buffer.Load(block, writeType)
s.Unlock()
return nil
}
func (s *dbSeries) OnRetrieveBlock(
id ident.ID,
tags ident.TagIterator,
startTime time.Time,
segment ts.Segment,
nsCtx namespace.Context,
) {
var (
b block.DatabaseBlock
list *block.WiredList
)
s.Lock()
defer func() {
s.Unlock()
if b != nil && list != nil {
// 1) We need to update the WiredList so that blocks that were read from disk
// can enter the list (OnReadBlock is only called for blocks that
// were read from memory, regardless of whether the data originated
// from disk or a buffer rotation.)
// 2) We must perform this action outside of the lock to prevent deadlock
// with the WiredList itself when it tries to call OnEvictedFromWiredList
// on the same series that is trying to perform a blocking update.
// 3) Doing this outside of the lock is safe because updating the
// wired list is asynchronous already (Update just puts the block in
// a channel to be processed later.)
// 4) We have to perform a blocking update because in this flow, the block
// is not already in the wired list so we need to make sure that the WiredList
// takes control of its lifecycle.
list.BlockingUpdate(b)
}
}()
if !id.Equal(s.id) {
return
}
b = s.opts.DatabaseBlockOptions().DatabaseBlockPool().Get()
blockSize := s.opts.RetentionOptions().BlockSize()
b.ResetFromDisk(startTime, blockSize, segment, s.id, nsCtx)
// NB(r): Blocks retrieved have been triggered by a read, so set the last
// read time as now so caching policies are followed.
b.SetLastReadTime(s.now())
// If we retrieved this from disk then we directly emplace it
s.addBlockWithLock(b)
list = s.opts.DatabaseBlockOptions().WiredList()
}
// OnReadBlock is only called for blocks that were read from memory, regardless of
// whether the data originated from disk or buffer rotation.
func (s *dbSeries) OnReadBlock(b block.DatabaseBlock) {
if list := s.opts.DatabaseBlockOptions().WiredList(); list != nil {
// The WiredList is only responsible for managing the lifecycle of blocks
// retrieved from disk.
if b.WasRetrievedFromDisk() {
// 1) Need to update the WiredList so it knows which blocks have been
// most recently read.
// 2) We do a non-blocking update here to prevent deadlock with the
// WiredList calling OnEvictedFromWiredList on the same series since
// OnReadBlock is usually called within the context of a read lock
// on this series.
// 3) Its safe to do a non-blocking update because the wired list has
// already been exposed to this block, so even if the wired list drops
// this update, it will still manage this blocks lifecycle.
list.NonBlockingUpdate(b)
}
}
}
func (s *dbSeries) OnEvictedFromWiredList(id ident.ID, blockStart time.Time) {
s.Lock()
defer s.Unlock()
// Should never happen
if !id.Equal(s.id) {
return
}
block, ok := s.cachedBlocks.BlockAt(blockStart)
if ok {
if !block.WasRetrievedFromDisk() {
// Should never happen - invalid application state could cause data loss
instrument.EmitAndLogInvariantViolation(
s.opts.InstrumentOptions(), func(l *zap.Logger) {
l.With(
zap.String("id", id.String()),
zap.Time("blockStart", blockStart),
).Error("tried to evict block that was not retrieved from disk")
})
return
}
s.cachedBlocks.RemoveBlockAt(blockStart)
}
}
func (s *dbSeries) WarmFlush(
ctx context.Context,
blockStart time.Time,
persistFn persist.DataFn,
nsCtx namespace.Context,
) (FlushOutcome, error) {
// Need a write lock because the buffer WarmFlush method mutates
// state (by performing a pro-active merge).
s.Lock()
outcome, err := s.buffer.WarmFlush(ctx, blockStart,
persist.NewMetadata(s.metadata), persistFn, nsCtx)
s.Unlock()
return outcome, err
}
func (s *dbSeries) Snapshot(
ctx context.Context,
blockStart time.Time,
persistFn persist.DataFn,
nsCtx namespace.Context,
) error {
// Need a write lock because the buffer Snapshot method mutates
// state (by performing a pro-active merge).
s.Lock()
err := s.buffer.Snapshot(ctx, blockStart,
persist.NewMetadata(s.metadata), persistFn, nsCtx)
s.Unlock()
return err
}
func (s *dbSeries) ColdFlushBlockStarts(blockStates BootstrappedBlockStateSnapshot) OptimizedTimes {
s.RLock()
defer s.RUnlock()
return s.buffer.ColdFlushBlockStarts(blockStates.Snapshot)
}
func (s *dbSeries) Bootstrap(nsCtx namespace.Context) error {
// NB(r): Need to hold the lock the whole time since
// this needs to be consistent view for a tick to see.
s.Lock()
defer s.Unlock()
s.bootstrap.Lock()
bootstrapBuffer := s.bootstrap.buffer
s.bootstrap.buffer = nil
s.bootstrap.Unlock()
if bootstrapBuffer == nil {
return nil
}
// NB(r): Now bootstrapped need to move bootstrap writes to the
// normal series buffer to make them visible to DB.
// We store these bootstrap writes in a side buffer so that we don't
// need to take the series lock and contend with normal writes
// that flow into the DB while bootstrapping which can significantly
// interrupt write latency and cause entire DB to stall/degrade in performance.
return bootstrapBuffer.MoveTo(s.buffer, nsCtx)
}
func (s *dbSeries) Close() {
s.bootstrap.Lock()
if s.bootstrap.buffer != nil {
s.bootstrap.buffer = nil
}
s.bootstrap.Unlock()
s.Lock()
defer s.Unlock()
// See Reset() for why these aren't finalized.
s.id = nil
s.metadata = doc.Document{}
s.uniqueIndex = 0
switch s.opts.CachePolicy() {
case CacheLRU:
// In the CacheLRU case, blocks that were retrieved from disk are owned
// by the WiredList and should not be closed here. They will eventually
// be evicted and closed by the WiredList when it needs to make room
// for new blocks.
default:
// This call closes the blocks as well.
s.cachedBlocks.RemoveAll()
}
// Reset (not close) underlying resources because the series will go
// back into the pool and be re-used.
s.buffer.Reset(databaseBufferResetOptions{Options: s.opts})
s.cachedBlocks.Reset()
if s.pool != nil {
s.pool.Put(s)
}
}
func (s *dbSeries) Reset(opts DatabaseSeriesOptions) {
// NB(r): We explicitly do not place the ID back into an
// existing pool as high frequency users of series IDs such
// as the commit log need to use the reference without the
// overhead of ownership tracking. In addition, the blocks
// themselves have a reference to the ID which is required
// for the LRU/WiredList caching strategy eviction process.
// Since the wired list can still have a reference to a
// DatabaseBlock for which the corresponding DatabaseSeries
// has been closed, its important that the ID itself is still
// available because the process of kicking a DatabaseBlock
// out of the WiredList requires the ID.
//
// Since series are purged so infrequently the overhead
// of not releasing back an ID to a pool is amortized over
// a long period of time.
//
// The same goes for the series tags.
s.Lock()
s.id = opts.ID
s.metadata = opts.Metadata
s.uniqueIndex = opts.UniqueIndex
s.cachedBlocks.Reset()
s.buffer.Reset(databaseBufferResetOptions{
BlockRetriever: opts.BlockRetriever,
Options: opts.Options,
})
s.opts = opts.Options
s.blockRetriever = opts.BlockRetriever
s.onRetrieveBlock = opts.OnRetrieveBlock
s.blockOnEvictedFromWiredList = opts.OnEvictedFromWiredList
s.Unlock()
}