mirror of
https://github.com/featurebasedb/featurebase.git
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102 lines
2.1 KiB
Go
102 lines
2.1 KiB
Go
// Copyright 2022 Molecula Corp. (DBA FeatureBase).
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// SPDX-License-Identifier: Apache-2.0
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package ctl
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import (
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"context"
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"encoding/hex"
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"fmt"
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"io"
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"os"
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"strings"
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"github.com/featurebasedb/featurebase/v3/logger"
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"github.com/featurebasedb/featurebase/v3/rbf"
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)
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// RBFDumpCommand represents a command for dumping raw data for an RBF page.
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type RBFDumpCommand struct {
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// Filepath to the RBF database.
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Path string
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// Page numbers to print.
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Pgnos []uint32
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// Standard input/output
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stdout io.Writer
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logDest logger.Logger
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}
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// NewRBFDumpCommand returns a new instance of RBFDumpCommand.
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func NewRBFDumpCommand(logdest logger.Logger) *RBFDumpCommand {
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return &RBFDumpCommand{
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stdout: os.Stdout,
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logDest: logdest,
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}
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}
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// Run executes the export.
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func (cmd *RBFDumpCommand) Run(ctx context.Context) error {
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// Open database.
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db := rbf.NewDB(cmd.Path, nil)
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if err := db.Open(); err != nil {
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return err
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}
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defer db.Close()
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// Execute with a transaction.
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tx, err := db.Begin(false)
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if err != nil {
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return err
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}
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defer tx.Rollback()
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// Fetch each page & dump.
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for _, pgno := range cmd.Pgnos {
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buf, err := tx.PageData(pgno)
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if err != nil {
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return err
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}
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fmt.Fprintf(cmd.stdout, "## PAGE %d\n", pgno)
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fmt.Fprintln(cmd.stdout, compressedHexDump(buf))
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fmt.Fprintln(cmd.stdout, "")
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}
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return nil
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}
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func compressedHexDump(b []byte) string {
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const prefixN = len("00000000")
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var output []string
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var prev string
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var ellipsis bool
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lines := strings.Split(strings.TrimSpace(hex.Dump(b)), "\n")
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for i, line := range lines {
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// Add line to output if it is not repeating or the last line.
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if i == 0 || i == len(lines)-1 || trimPrefixN(line, prefixN) != trimPrefixN(prev, prefixN) {
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output = append(output, line)
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prev, ellipsis = line, false
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continue
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}
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// Add an ellipsis for the first duplicate line.
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if !ellipsis {
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output = append(output, "...")
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ellipsis = true
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continue
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}
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}
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return strings.Join(output, "\n")
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}
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// trimPrefixN trims n bytes from the beginning of a string.
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func trimPrefixN(s string, n int) string {
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if len(s) < n {
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return ""
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}
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return s[n:]
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}
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