mirror of
https://github.com/prometheus/prometheus.git
synced 2024-11-09 23:24:05 -08:00
Add basic initial developer docs for TSDB (#9451)
* Add basic initial developer docs for TSDB There's a decent amount of content already out there (blog posts, conference talks, etc), but: * when they get stale, they don't tend to get updated * they still leave me with questions that I'ld like to answer for developers (like me) who want to use, or work with, TSDB What I propose is developer docs inside the prometheus repository. Easy to find and harness the power of the community to expand it and keep it up to date. * perfect is the enemy of good. Let's have a base and incrementally improve * Markdown docs should be broad but not too deep. Source code comments can complement them, and are the ideal place for implementation details. Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * use example code that works out of the box Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * Apply suggestions from code review Co-authored-by: Ganesh Vernekar <15064823+codesome@users.noreply.github.com> Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * PR feedback Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * more docs Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * PR feedback Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * Apply suggestions from code review Signed-off-by: Dieter Plaetinck <dieter@grafana.com> Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com> * Apply suggestions from code review Signed-off-by: Dieter Plaetinck <dieter@grafana.com> Co-authored-by: Ganesh Vernekar <15064823+codesome@users.noreply.github.com> * feedback Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * Update tsdb/docs/usage.md Signed-off-by: Dieter Plaetinck <dieter@grafana.com> Co-authored-by: Ganesh Vernekar <15064823+codesome@users.noreply.github.com> * final tweaks Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * workaround docs versioning issue Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * Move example code to real executable, testable example. Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * cleanup example test and make sure it always reproduces Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * obtain temp dir in a way that works with older Go versions Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * Fix Ganesh's comments Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com> Co-authored-by: Ganesh Vernekar <15064823+codesome@users.noreply.github.com> Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com> Co-authored-by: Ganesh Vernekar <ganeshvern@gmail.com>
This commit is contained in:
Dieter Plaetinck
GitHub
parent
49d8f02c1f
commit
0fac9bb859
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@ -111,7 +111,7 @@ For more information on building, running, and developing on the new React-based
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## More information
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* The source code is periodically indexed: [Prometheus Core](https://pkg.go.dev/github.com/prometheus/prometheus).
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* The source code is periodically indexed, but due to an issue with versioning, the "latest" docs shown on Godoc are outdated. Instead, you can use [the docs for v2.31.1](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab).
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* You will find a CircleCI configuration in [`.circleci/config.yml`](.circleci/config.yml).
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* See the [Community page](https://prometheus.io/community) for how to reach the Prometheus developers and users on various communication channels.
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@ -131,7 +131,7 @@ the Prometheus server will be able to see them.
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### The SD interface
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A Service Discovery (SD) mechanism has to discover targets and provide them to Prometheus. We expect similar targets to be grouped together, in the form of a [target group](https://pkg.go.dev/github.com/prometheus/prometheus/discovery/targetgroup#Group). The SD mechanism sends the targets down to prometheus as list of target groups.
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A Service Discovery (SD) mechanism has to discover targets and provide them to Prometheus. We expect similar targets to be grouped together, in the form of a [target group](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab/discovery/targetgroup#Group). The SD mechanism sends the targets down to prometheus as list of target groups.
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An SD mechanism has to implement the `Discoverer` Interface:
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```go
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@ -173,9 +173,9 @@ func (f QueryableFunc) Querier(ctx context.Context, mint, maxt int64) (Querier,
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// Operations on the Appender interface are not goroutine-safe.
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type Appender interface {
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// Append adds a sample pair for the given series.
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// An optional reference number can be provided to accelerate calls.
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// A reference number is returned which can be used to add further
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// samples in the same or later transactions.
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// An optional series reference can be provided to accelerate calls.
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// A series reference number is returned which can be used to add further
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// samples to the given series in the same or later transactions.
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// Returned reference numbers are ephemeral and may be rejected in calls
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// to Append() at any point. Adding the sample via Append() returns a new
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// reference number.
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@ -1,16 +1,25 @@
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# TSDB
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[](https://pkg.go.dev/github.com/prometheus/prometheus/tsdb)
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[](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab/tsdb)
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This directory contains the Prometheus storage layer that is used in its 2.x releases.
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This directory contains the Prometheus TSDB (Time Series DataBase) library,
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which handles storage and querying of all Prometheus v2 data.
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A writeup of its design can be found [here](https://fabxc.org/blog/2017-04-10-writing-a-tsdb/).
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Due to an issue with versioning, the "latest" docs shown on Godoc are outdated.
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Instead you may use [the docs for v2.31.1](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab)
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Based on the Gorilla TSDB [white papers](http://www.vldb.org/pvldb/vol8/p1816-teller.pdf).
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## Documentation
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Video: [Storing 16 Bytes at Scale](https://youtu.be/b_pEevMAC3I) from [PromCon 2017](https://promcon.io/2017-munich/).
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* [Data format](docs/format/README.md).
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* [Usage](docs/usage.md).
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* [Bstream details](docs/bstream.md).
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## External resources
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* A writeup of the original design can be found [here](https://fabxc.org/blog/2017-04-10-writing-a-tsdb/).
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* Video: [Storing 16 Bytes at Scale](https://youtu.be/b_pEevMAC3I) from [PromCon 2017](https://promcon.io/2017-munich/).
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* Compression is based on the Gorilla TSDB [white paper](http://www.vldb.org/pvldb/vol8/p1816-teller.pdf).
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See also the [format documentation](docs/format/README.md) and [bstream details](docs/bstream.md).
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A series of blog posts explaining different components of TSDB:
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* [The Head Block](https://ganeshvernekar.com/blog/prometheus-tsdb-the-head-block/)
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@ -109,7 +109,7 @@ type Meta struct {
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MinTime, MaxTime int64
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}
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// Iterator iterates over the chunk of a time series.
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// Iterator iterates over the chunks of a single time series.
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type Iterator interface {
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// At returns the current meta.
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// It depends on implementation if the chunk is populated or not.
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@ -51,7 +51,7 @@ const (
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MintMaxtSize = 8
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// SeriesRefSize is the size of series reference on disk.
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SeriesRefSize = 8
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// HeadChunkFileHeaderSize is the total size of the header for the head chunk file.
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// HeadChunkFileHeaderSize is the total size of the header for a head chunk file.
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HeadChunkFileHeaderSize = SegmentHeaderSize
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// MaxHeadChunkFileSize is the max size of a head chunk file.
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MaxHeadChunkFileSize = 128 * 1024 * 1024 // 128 MiB.
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@ -124,19 +124,20 @@ type ChunkDiskMapper struct {
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// from which chunks are served till they are flushed and are ready for m-mapping.
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chunkBuffer *chunkBuffer
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// If 'true', it indicated that the maxt of all the on-disk files were set
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// after iterating through all the chunks in those files.
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// Whether the maxt field is set for all mmapped chunk files tracked within the mmappedChunkFiles map.
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// This is done after iterating through all the chunks in those files using the IterateAllChunks method.
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fileMaxtSet bool
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closed bool
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}
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// mmappedChunkFile provides mmapp access to an entire head chunks file that holds many chunks.
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type mmappedChunkFile struct {
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byteSlice ByteSlice
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maxt int64
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maxt int64 // Max timestamp among all of this file's chunks.
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}
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// NewChunkDiskMapper returns a new writer against the given directory
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// NewChunkDiskMapper returns a new ChunkDiskMapper against the given directory
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// using the default head chunk file duration.
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// NOTE: 'IterateAllChunks' method needs to be called at least once after creating ChunkDiskMapper
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// to set the maxt of all the file.
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@ -172,6 +173,7 @@ func NewChunkDiskMapper(dir string, pool chunkenc.Pool, writeBufferSize int) (*C
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return m, m.openMMapFiles()
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}
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// openMMapFiles opens all files within dir for mmapping.
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func (cdm *ChunkDiskMapper) openMMapFiles() (returnErr error) {
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cdm.mmappedChunkFiles = map[int]*mmappedChunkFile{}
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cdm.closers = map[int]io.Closer{}
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@ -254,7 +256,7 @@ func listChunkFiles(dir string) (map[int]string, error) {
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}
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// repairLastChunkFile deletes the last file if it's empty.
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// Because we don't fsync when creating these file, we could end
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// Because we don't fsync when creating these files, we could end
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// up with an empty file at the end during an abrupt shutdown.
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func repairLastChunkFile(files map[int]string) (_ map[int]string, returnErr error) {
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lastFile := -1
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@ -350,7 +352,7 @@ func (cdm *ChunkDiskMapper) WriteChunk(seriesRef HeadSeriesRef, mint, maxt int64
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return chkRef, nil
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}
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// shouldCutNewFile decides the cutting of a new file based on time and size retention.
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// shouldCutNewFile returns whether a new file should be cut, based on time and size retention.
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// Size retention: because depending on the system architecture, there is a limit on how big of a file we can m-map.
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// Time retention: so that we can delete old chunks with some time guarantee in low load environments.
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func (cdm *ChunkDiskMapper) shouldCutNewFile(chunkSize int) bool {
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@ -465,7 +467,7 @@ func (cdm *ChunkDiskMapper) flushBuffer() error {
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// Chunk returns a chunk from a given reference.
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func (cdm *ChunkDiskMapper) Chunk(ref ChunkDiskMapperRef) (chunkenc.Chunk, error) {
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cdm.readPathMtx.RLock()
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// We hold this read lock for the entire duration because if the Close()
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// We hold this read lock for the entire duration because if Close()
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// is called, the data in the byte slice will get corrupted as the mmapped
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// file will be closed.
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defer cdm.readPathMtx.RUnlock()
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@ -575,8 +577,8 @@ func (cdm *ChunkDiskMapper) Chunk(ref ChunkDiskMapperRef) (chunkenc.Chunk, error
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return chk, nil
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}
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// IterateAllChunks iterates on all the chunks in its byte slices in the order of the head chunk file sequence
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// and runs the provided function on each chunk. It returns on the first error encountered.
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// IterateAllChunks iterates all mmappedChunkFiles (in order of head chunk file name/number) and all the chunks within it
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// and runs the provided function with information about each chunk. It returns on the first error encountered.
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// NOTE: This method needs to be called at least once after creating ChunkDiskMapper
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// to set the maxt of all the file.
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func (cdm *ChunkDiskMapper) IterateAllChunks(f func(seriesRef HeadSeriesRef, chunkRef ChunkDiskMapperRef, mint, maxt int64, numSamples uint16) error) (err error) {
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@ -825,7 +827,7 @@ func closeAllFromMap(cs map[int]io.Closer) error {
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const inBufferShards = 128 // 128 is a randomly chosen number.
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// chunkBuffer is a thread safe buffer for chunks.
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// chunkBuffer is a thread safe lookup table for chunks by their ref.
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type chunkBuffer struct {
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inBufferChunks [inBufferShards]map[ChunkDiskMapperRef]chunkenc.Chunk
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inBufferChunksMtxs [inBufferShards]sync.RWMutex
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@ -596,6 +596,9 @@ func validateOpts(opts *Options, rngs []int64) (*Options, []int64) {
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return opts, rngs
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}
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// open returns a new DB in the given directory.
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// It initializes the lockfile, WAL, compactor, and Head (by replaying the WAL), and runs the database.
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// It is not safe to open more than one DB in the same directory.
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func open(dir string, l log.Logger, r prometheus.Registerer, opts *Options, rngs []int64, stats *DBStats) (_ *DB, returnedErr error) {
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if err := os.MkdirAll(dir, 0o777); err != nil {
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return nil, err
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71
tsdb/docs/usage.md
Normal file
71
tsdb/docs/usage.md
Normal file
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@ -0,0 +1,71 @@
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# Usage
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TSDB can be - and is - used by other applications such as [Cortex](https://cortexmetrics.io/) and [Thanos](https://thanos.io/).
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This directory contains documentation for any developers who wish to work on or with TSDB.
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For a full example of instantiating a database, adding and querying data, see the [tsdb example in the docs](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab/tsdb).
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`tsdb/db_test.go` also demonstrates various specific usages of the TSDB library.
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## Instantiating a database
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Callers should use [`tsdb.Open`](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab/tsdb#Open) to open a TSDB
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(the directory may be new or pre-existing).
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This returns a [`*tsdb.DB`](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab/tsdb#DB) which is the actual database.
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A `DB` has the following main components:
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* Compactor: a [leveled compactor](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab/tsdb#LeveledCompactor). Note: it is currently the only compactor implementation. It runs automatically.
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* [`Head`](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab/tsdb#DB.Head)
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* [Blocks (persistent blocks)](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab/tsdb#DB.Blocks)
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The `Head` is responsible for a lot. Here are its main components:
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* [WAL](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab/tsdb/wal#WAL) (Write Ahead Log).
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* [`stripeSeries`](https://github.com/prometheus/prometheus/blob/411021ada9ab41095923b8d2df9365b632fd40c3/tsdb/head.go#L1292):
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this holds all the active series by linking to [`memSeries`](https://github.com/prometheus/prometheus/blob/411021ada9ab41095923b8d2df9365b632fd40c3/tsdb/head.go#L1462)
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by an ID (aka "ref") and by labels hash.
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* Postings list (reverse index): For any label-value pair, holds all the corresponding series refs. Used for queries.
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* Tombstones.
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## Adding data
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Use [`db.Appender()`](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab/tsdb#DB.Appender) to obtain an "appender".
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The [golang docs](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab/storage#Appender) speak mostly for themselves.
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Remember:
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* Use `Commit()` to add the samples to the DB and update the WAL.
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* Create a new appender each time you commit.
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* Appenders are not concurrency safe, but scrapes run concurrently and as such, leverage multiple appenders concurrently.
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This reduces contention, although Commit() contend the same critical section (writing to the WAL is serialized), and may
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inflate append tail latency if multiple appenders try to commit at the same time.
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Append may reject data due to these conditions:
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1) `timestamp < minValidTime` where `minValidTime` is the highest of:
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* the maxTime of the last block (i.e. the last truncation time of Head) - updated via [`Head.Truncate()`](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab/tsdb#Head.Truncate) and [`DB.compactHead()`](https://github.com/prometheus/prometheus/blob/411021ada9ab41095923b8d2df9365b632fd40c3/tsdb/db.go#L968)
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* `tsdb.min-block-duration/2` older than the max time in the Head block. Note that while technically `storage.tsdb.min-block-duration` is configurable, it's a hidden option and changing it is discouraged. So We can assume this value to be 2h.
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Breaching this condition results in "out of bounds" errors.
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The first condition assures the block that will be generated doesn't overlap with the previous one (which simplifies querying)
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The second condition assures the sample won't go into the so called "compaction window", that is the section of the data that might be in process of being saved into a persistent block on disk. (because that logic runs concurrently with ingestion without a lock)
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2) The labels don't validate. (if the set is empty or contains duplicate label names)
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3) If the sample, for the respective series (based on all the labels) is out of order or has a different value for the last (highest) timestamp seen. (results in `storage.ErrOutOfOrderSample` and `storage.ErrDuplicateSampleForTimestamp` respectively)
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`Commit()` may also refuse data that is out of order with respect to samples that were added via a different appender.
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## Querying data
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Use [`db.Querier()`](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab/tsdb#DB.Querier) to obtain a "querier".
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The [golang docs](https://pkg.go.dev/github.com/prometheus/prometheus@v1.8.2-0.20211105201321-411021ada9ab/storage#Querier) speak mostly for themselves.
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Remember:
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* A querier can only see data that was committed when it was created. This limits the lifetime of a querier.
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* A querier should be closed when you're done with it.
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* Use mint/maxt to avoid loading unneeded data.
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## Example code
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Find the example code for ingesting samples and querying them in [`tsdb/example_test.go`](../example_test.go)
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112
tsdb/example_test.go
Normal file
112
tsdb/example_test.go
Normal file
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@ -0,0 +1,112 @@
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// Copyright 2021 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
|
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// distributed under the License is distributed on an "AS IS" BASIS,
|
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
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// See the License for the specific language governing permissions and
|
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// limitations under the License.
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package tsdb
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import (
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"context"
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"fmt"
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"math"
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"testing"
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"time"
|
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"github.com/stretchr/testify/require"
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"github.com/prometheus/prometheus/model/labels"
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)
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func TestExample(t *testing.T) {
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// Create a random dir to work in. Open() doesn't require a pre-existing dir, but
|
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// we want to make sure not to make a mess where we shouldn't.
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dir := t.TempDir()
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// Open a TSDB for reading and/or writing.
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db, err := Open(dir, nil, nil, DefaultOptions(), nil)
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require.NoError(t, err)
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// Open an appender for writing.
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app := db.Appender(context.Background())
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lbls := labels.FromStrings("foo", "bar")
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var appendedSamples []sample
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||||
|
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// Ref is 0 for the first append since we don't know the reference for the series.
|
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ts, v := time.Now().Unix(), 123.0
|
||||
ref, err := app.Append(0, lbls, ts, v)
|
||||
require.NoError(t, err)
|
||||
appendedSamples = append(appendedSamples, sample{ts, v})
|
||||
|
||||
// Another append for a second later.
|
||||
// Re-using the ref from above since it's the same series, makes append faster.
|
||||
time.Sleep(time.Second)
|
||||
ts, v = time.Now().Unix(), 124
|
||||
_, err = app.Append(ref, lbls, ts, v)
|
||||
require.NoError(t, err)
|
||||
appendedSamples = append(appendedSamples, sample{ts, v})
|
||||
|
||||
// Commit to storage.
|
||||
err = app.Commit()
|
||||
require.NoError(t, err)
|
||||
|
||||
// In case you want to do more appends after app.Commit(),
|
||||
// you need a new appender.
|
||||
// app = db.Appender(context.Background())
|
||||
//
|
||||
// ... adding more samples.
|
||||
//
|
||||
// Commit to storage.
|
||||
// err = app.Commit()
|
||||
// require.NoError(t, err)
|
||||
|
||||
// Open a querier for reading.
|
||||
querier, err := db.Querier(context.Background(), math.MinInt64, math.MaxInt64)
|
||||
require.NoError(t, err)
|
||||
|
||||
ss := querier.Select(false, nil, labels.MustNewMatcher(labels.MatchEqual, "foo", "bar"))
|
||||
var queriedSamples []sample
|
||||
for ss.Next() {
|
||||
series := ss.At()
|
||||
fmt.Println("series:", series.Labels().String())
|
||||
|
||||
it := series.Iterator()
|
||||
for it.Next() {
|
||||
ts, v := it.At()
|
||||
fmt.Println("sample", ts, v)
|
||||
queriedSamples = append(queriedSamples, sample{ts, v})
|
||||
}
|
||||
|
||||
require.NoError(t, it.Err())
|
||||
fmt.Println("it.Err():", it.Err())
|
||||
}
|
||||
require.NoError(t, ss.Err())
|
||||
fmt.Println("ss.Err():", ss.Err())
|
||||
ws := ss.Warnings()
|
||||
if len(ws) > 0 {
|
||||
fmt.Println("warnings:", ws)
|
||||
}
|
||||
err = querier.Close()
|
||||
require.NoError(t, err)
|
||||
|
||||
// Clean up any last resources when done.
|
||||
err = db.Close()
|
||||
require.NoError(t, err)
|
||||
|
||||
require.Equal(t, appendedSamples, queriedSamples)
|
||||
|
||||
// Output:
|
||||
// series: {foo="bar"}
|
||||
// sample <ts1> 123
|
||||
// sample <ts2> 124
|
||||
// it.Err(): <nil>
|
||||
// ss.Err(): <nil>
|
||||
}
|
||||
32
tsdb/head.go
32
tsdb/head.go
|
|
@ -992,12 +992,15 @@ func (h *Head) Stats(statsByLabelName string) *Stats {
|
|||
}
|
||||
}
|
||||
|
||||
// RangeHead allows querying Head via an IndexReader, ChunkReader and tombstones.Reader
|
||||
// but only within a restricted range. Used for queries and compactions.
|
||||
type RangeHead struct {
|
||||
head *Head
|
||||
mint, maxt int64
|
||||
}
|
||||
|
||||
// NewRangeHead returns a *RangeHead.
|
||||
// There are no restrictions on mint/maxt.
|
||||
func NewRangeHead(head *Head, mint, maxt int64) *RangeHead {
|
||||
return &RangeHead{
|
||||
head: head,
|
||||
|
|
@ -1284,15 +1287,17 @@ const (
|
|||
DefaultStripeSize = 1 << 14
|
||||
)
|
||||
|
||||
// stripeSeries locks modulo ranges of IDs and hashes to reduce lock contention.
|
||||
// stripeSeries holds series by HeadSeriesRef ("ID") and also by hash of their labels.
|
||||
// ID-based lookups via (getByID()) are preferred over getByHash() for performance reasons.
|
||||
// It locks modulo ranges of IDs and hashes to reduce lock contention.
|
||||
// The locks are padded to not be on the same cache line. Filling the padded space
|
||||
// with the maps was profiled to be slower – likely due to the additional pointer
|
||||
// dereferences.
|
||||
type stripeSeries struct {
|
||||
size int
|
||||
series []map[chunks.HeadSeriesRef]*memSeries
|
||||
hashes []seriesHashmap
|
||||
locks []stripeLock
|
||||
series []map[chunks.HeadSeriesRef]*memSeries // Sharded by ref. A series ref is the value of `size` when the series was being newly added.
|
||||
hashes []seriesHashmap // Sharded by label hash.
|
||||
locks []stripeLock // Sharded by ref for series access, by label hash for hashes access.
|
||||
seriesLifecycleCallback SeriesLifecycleCallback
|
||||
}
|
||||
|
||||
|
|
@ -1466,17 +1471,24 @@ type memSeries struct {
|
|||
|
||||
ref chunks.HeadSeriesRef
|
||||
lset labels.Labels
|
||||
mmappedChunks []*mmappedChunk
|
||||
mmMaxTime int64 // Max time of any mmapped chunk, only used during WAL replay.
|
||||
headChunk *memChunk
|
||||
mmappedChunks []*mmappedChunk // Immutable chunks on disk that have not yet gone into a block, in order of ascending time stamps.
|
||||
mmMaxTime int64 // Max time of any mmapped chunk, only used during WAL replay.
|
||||
headChunk *memChunk // Most recent chunk in memory that's still being built.
|
||||
chunkRange int64
|
||||
firstChunkID int
|
||||
|
||||
nextAt int64 // Timestamp at which to cut the next chunk.
|
||||
sampleBuf [4]sample
|
||||
nextAt int64 // Timestamp at which to cut the next chunk.
|
||||
|
||||
// We keep the last 4 samples here (in addition to appending them to the chunk) so we don't need coordination between appender and querier.
|
||||
// Even the most compact encoding of a sample takes 2 bits, so the last byte is not contended.
|
||||
sampleBuf [4]sample
|
||||
|
||||
pendingCommit bool // Whether there are samples waiting to be committed to this series.
|
||||
|
||||
app chunkenc.Appender // Current appender for the chunk.
|
||||
// Current appender for the head chunk. Set when a new head chunk is cut.
|
||||
// It is nil only if headChunk is nil. E.g. if there was an appender that created a new series, but rolled back the commit
|
||||
// (the first sample would create a headChunk, hence appender, but rollback skipped it while the Append() call would create a series).
|
||||
app chunkenc.Appender
|
||||
|
||||
memChunkPool *sync.Pool
|
||||
|
||||
|
|
|
|||
|
|
@ -114,7 +114,7 @@ func (h *Head) Appender(_ context.Context) storage.Appender {
|
|||
}
|
||||
|
||||
func (h *Head) appender() *headAppender {
|
||||
appendID, cleanupAppendIDsBelow := h.iso.newAppendID()
|
||||
appendID, cleanupAppendIDsBelow := h.iso.newAppendID() // Every appender gets an ID that is cleared upon commit/rollback.
|
||||
|
||||
// Allocate the exemplars buffer only if exemplars are enabled.
|
||||
var exemplarsBuf []exemplarWithSeriesRef
|
||||
|
|
@ -224,10 +224,10 @@ type headAppender struct {
|
|||
minValidTime int64 // No samples below this timestamp are allowed.
|
||||
mint, maxt int64
|
||||
|
||||
series []record.RefSeries
|
||||
samples []record.RefSample
|
||||
exemplars []exemplarWithSeriesRef
|
||||
sampleSeries []*memSeries
|
||||
series []record.RefSeries // New series held by this appender.
|
||||
samples []record.RefSample // New samples held by this appender.
|
||||
exemplars []exemplarWithSeriesRef // New exemplars held by this appender.
|
||||
sampleSeries []*memSeries // Series corresponding to the samples held by this appender (using corresponding slice indices - same series may appear more than once).
|
||||
|
||||
appendID, cleanupAppendIDsBelow uint64
|
||||
closed bool
|
||||
|
|
@ -361,6 +361,7 @@ func (a *headAppender) GetRef(lset labels.Labels) (storage.SeriesRef, labels.Lab
|
|||
return storage.SeriesRef(s.ref), s.lset
|
||||
}
|
||||
|
||||
// log writes all headAppender's data to the WAL.
|
||||
func (a *headAppender) log() error {
|
||||
if a.head.wal == nil {
|
||||
return nil
|
||||
|
|
@ -412,6 +413,7 @@ func exemplarsForEncoding(es []exemplarWithSeriesRef) []record.RefExemplar {
|
|||
return ret
|
||||
}
|
||||
|
||||
// Commit writes to the WAL and adds the data to the Head.
|
||||
func (a *headAppender) Commit() (err error) {
|
||||
if a.closed {
|
||||
return ErrAppenderClosed
|
||||
|
|
@ -481,7 +483,7 @@ func (s *memSeries) append(t int64, v float64, appendID uint64, chunkDiskMapper
|
|||
|
||||
if c == nil {
|
||||
if len(s.mmappedChunks) > 0 && s.mmappedChunks[len(s.mmappedChunks)-1].maxTime >= t {
|
||||
// Out of order sample. Sample timestamp is already in the mmaped chunks, so ignore it.
|
||||
// Out of order sample. Sample timestamp is already in the mmapped chunks, so ignore it.
|
||||
return false, false
|
||||
}
|
||||
// There is no chunk in this series yet, create the first chunk for the sample.
|
||||
|
|
@ -583,6 +585,7 @@ func (s *memSeries) mmapCurrentHeadChunk(chunkDiskMapper *chunks.ChunkDiskMapper
|
|||
})
|
||||
}
|
||||
|
||||
// Rollback removes the samples and exemplars from headAppender and writes any series to WAL.
|
||||
func (a *headAppender) Rollback() (err error) {
|
||||
if a.closed {
|
||||
return ErrAppenderClosed
|
||||
|
|
|
|||
|
|
@ -175,6 +175,8 @@ func (h *headIndexReader) Series(ref storage.SeriesRef, lbls *labels.Labels, chk
|
|||
return nil
|
||||
}
|
||||
|
||||
// chunkID returns the ID corresponding to .mmappedChunks[pos]
|
||||
// (head chunk if pos==len(mmappedChunks))
|
||||
func (s *memSeries) chunkID(pos int) int {
|
||||
return pos + s.firstChunkID
|
||||
}
|
||||
|
|
@ -288,9 +290,9 @@ func (h *headChunkReader) Chunk(ref chunks.ChunkRef) (chunkenc.Chunk, error) {
|
|||
}, nil
|
||||
}
|
||||
|
||||
// chunk returns the chunk for the chunk id from memory or by m-mapping it from the disk.
|
||||
// chunk returns the chunk for the chunkID from memory or by m-mapping it from the disk.
|
||||
// If garbageCollect is true, it means that the returned *memChunk
|
||||
// (and not the chunkenc.Chunk inside it) can be garbage collected after it's usage.
|
||||
// (and not the chunkenc.Chunk inside it) can be garbage collected after its usage.
|
||||
func (s *memSeries) chunk(id int, chunkDiskMapper *chunks.ChunkDiskMapper) (chunk *memChunk, garbageCollect bool, err error) {
|
||||
// ix represents the index of chunk in the s.mmappedChunks slice. The chunk id's are
|
||||
// incremented by 1 when new chunk is created, hence (id - firstChunkID) gives the slice index.
|
||||
|
|
@ -335,7 +337,7 @@ func (c *safeChunk) Iterator(reuseIter chunkenc.Iterator) chunkenc.Iterator {
|
|||
return it
|
||||
}
|
||||
|
||||
// iterator returns a chunk iterator.
|
||||
// iterator returns a chunk iterator for the requested chunkID.
|
||||
// It is unsafe to call this concurrently with s.append(...) without holding the series lock.
|
||||
func (s *memSeries) iterator(id int, isoState *isolationState, chunkDiskMapper *chunks.ChunkDiskMapper, it chunkenc.Iterator) chunkenc.Iterator {
|
||||
c, garbageCollect, err := s.chunk(id, chunkDiskMapper)
|
||||
|
|
@ -439,6 +441,8 @@ func (s *memSeries) iterator(id int, isoState *isolationState, chunkDiskMapper *
|
|||
}
|
||||
}
|
||||
|
||||
// memSafeIterator returns values from the wrapped stopIterator
|
||||
// except the last 4, which come from buf.
|
||||
type memSafeIterator struct {
|
||||
stopIterator
|
||||
|
||||
|
|
@ -482,6 +486,8 @@ func (it *memSafeIterator) At() (int64, float64) {
|
|||
return s.t, s.v
|
||||
}
|
||||
|
||||
// stopIterator wraps an Iterator, but only returns the first
|
||||
// stopAfter values, if initialized with i=-1.
|
||||
type stopIterator struct {
|
||||
chunkenc.Iterator
|
||||
|
||||
|
|
|
|||
|
|
@ -12,6 +12,7 @@
|
|||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
// Package record contains the various record types used for encoding various Head block data in the WAL and in-memory snapshot.
|
||||
package record
|
||||
|
||||
import (
|
||||
|
|
|
|||
Loading…
Reference in a new issue