david
42b03db2fa
Flush sealed head chunks to ULID-named block directories on disk. Each block contains CRC'd chunk segment files (mmap'd for reads), a binary index (symbol table, series, postings with TOC), and a meta.json written last as the immutability gate. WAL is truncated after block fsync, preserving the crash-safety ording invariant.
56 lines
1.4 KiB
Go
56 lines
1.4 KiB
Go
package block
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import (
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"encoding/json"
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"os"
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"path/filepath"
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)
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// BlockMeta describes a block on disk.
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type BlockMeta struct {
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ULID string `json:"ulid"`
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MinTime int64 `json:"minTime"`
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MaxTime int64 `json:"maxTime"`
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Stats BlockStats `json:"stats"`
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Compaction CompactionInfo `json:"compaction"`
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Version int `json:"version"`
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}
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// BlockStats holds summary statistics for a block.
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type BlockStats struct {
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NumSamples int `json:"numSamples"`
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NumSeries int `json:"numSeries"`
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NumChunks int `json:"numChunks"`
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}
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// CompactionInfo records the block's compaction lineage.
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type CompactionInfo struct {
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Level int `json:"level"`
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Sources []string `json:"sources"`
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}
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const metaFilename = "meta.json"
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// readMeta reads a block's meta.json from the given block directory.
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func readMeta(dir string) (BlockMeta, error) {
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data, err := os.ReadFile(filepath.Join(dir, metaFilename))
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if err != nil {
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return BlockMeta{}, err
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}
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var m BlockMeta
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if err := json.Unmarshal(data, &m); err != nil {
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return BlockMeta{}, err
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}
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return m, nil
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}
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// writeMeta writes a block's meta.json to the given block directory.
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// This is the last file written when creating a block — the immutability gate.
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func writeMeta(dir string, m BlockMeta) error {
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data, err := json.MarshalIndent(m, "", " ")
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if err != nil {
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return err
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}
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return os.WriteFile(filepath.Join(dir, metaFilename), data, 0644)
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}
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