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p9trace: file system trace reader
1 parent 510f6a0 commit 7ad7123

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7 files changed

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7 files changed

+585
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‎p9trace/deps.go‎

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// This file is not ignored by 'go mod tidy',
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// to keep leveldb as a required module.
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//go:build never
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package p9trace
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import _ "github.com/golang/leveldb/table"

‎p9trace/go.mod‎

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module 9fans.net/go/p9trace
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go 1.23.0
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require github.com/golang/leveldb v0.0.0-20170107010102-259d9253d719
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require github.com/golang/snappy v0.0.4 // indirect

‎p9trace/go.sum‎

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github.com/golang/leveldb v0.0.0-20170107010102-259d9253d719 h1:yahFtfWlyALYDkXw2ETowZqG4vi8hiE0yOEBOkpaXl0=
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github.com/golang/leveldb v0.0.0-20170107010102-259d9253d719/go.mod h1:etEpE0xVqxA0N3WNUa5wic5HCNSsQvYm+PFNmOnx2iU=
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github.com/golang/snappy v0.0.4 h1:yAGX7huGHXlcLOEtBnF4w7FQwA26wojNCwOYAEhLjQM=
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github.com/golang/snappy v0.0.4/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=

‎p9trace/reorder.go‎

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//go:build ignore
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// Reorder reorders the traces so that block pointers only ever point to earlier blocks
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// and writes the result to a single trace file.
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package main
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import (
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"bufio"
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"bytes"
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"compress/flate"
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"encoding/binary"
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"log"
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"os"
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"9fans.net/go/p9trace"
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)
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var all []*p9trace.Record
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var remap []uint32
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var nbad int
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var nextOut uint32
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var bw *bufio.Writer
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func main() {
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f, err := os.Create(os.Args[1])
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if err != nil {
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log.Fatal(err)
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}
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bw = bufio.NewWriterSize(f, 1<<20)
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for r := range p9trace.FileRecords(os.Args[2:]...) {
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all = append(all, r)
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if all[r.Addr] != r {
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panic("mismatch")
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}
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}
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println("loaded", all[173927], all[173927].Addr, all[173927].Tag)
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remap = make([]uint32, len(all))
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for addr, r := range all {
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if r.Tag == p9trace.TagSuper {
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writeRecord(uint32(addr))
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}
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}
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println(len(all), nbad, nextOut)
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bw.Flush()
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if err := bw.Flush(); err != nil {
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log.Fatal(err)
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}
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if err := f.Close(); err != nil {
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log.Fatal(err)
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}
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}
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var stack []*p9trace.Record
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func writeRecord(addr uint32) {
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if remap[addr] != 0 && remap[addr] != ^uint32(0) {
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return
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}
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r := all[addr]
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if all[r.Addr] != r {
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println("ALL", r.Addr, all[r.Addr], r)
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panic("all mismatch")
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}
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stack = append(stack, r)
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for p := range r.Pointers() {
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if r.Super != nil && p == &r.Super.Next {
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continue
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}
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if int(*p) > len(all) {
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println("BAD", r.Addr, *p, len(all))
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nbad++
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r.Dir = nil
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r.Ind = nil
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if r.Super != nil {
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*r.Super = p9trace.Super{}
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}
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break
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}
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}
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remap[r.Addr] = ^uint32(0)
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if r.Super != nil {
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r.Super.Next = 0
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}
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for p := range r.Pointers() {
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if *p == 0 {
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continue
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}
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if remap[*p] == 0 {
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writeRecord(*p)
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}
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if remap[*p] == ^uint32(0) {
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if *p == r.Addr {
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*p = 0
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continue
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}
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println("BLOCK LOOP", r.Addr, r.Tag, *p, all[*p].Addr, all[*p].Tag)
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for i, r1 := range stack {
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println("STACK #", i, r1.Addr, r1.Tag, r1, all[r1.Addr].Addr, all[r1.Addr].Tag, all[r1.Addr])
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}
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panic("block loop")
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}
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*p = remap[*p]
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}
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remap[r.Addr] = nextOut
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r.Addr = nextOut
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nextOut++
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if true {
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data, err := r.MarshalBinary()
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if err != nil {
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log.Fatal(err)
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}
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var hdr [2]byte
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if len(data) > p9trace.HeaderSize {
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var fb bytes.Buffer
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fw, err := flate.NewWriter(&fb, flate.BestSpeed)
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if err != nil {
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log.Fatal(err)
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}
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fw.Write(data)
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fw.Close()
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if fb.Len() < len(data) {
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binary.BigEndian.PutUint16(hdr[:], uint16(fb.Len())|0x8000)
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bw.Write(hdr[:])
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bw.Write(fb.Bytes())
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goto Done
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}
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}
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binary.BigEndian.PutUint16(hdr[:], uint16(len(data)))
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bw.Write(hdr[:])
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bw.Write(data)
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Done:
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}
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stack = stack[:len(stack)-1]
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}

‎p9trace/super.go‎

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//go:build ignore
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// Super is a port of the C "super.c" trace reading demo.
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// See https://github.com/9fans/p9trace/src/super.c.
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package main
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import (
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"fmt"
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"log"
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"os"
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"9fans.net/go/p9trace"
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)
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var (
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offset uint32 = ^uint32(0)
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last uint32
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next uint32
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count [p9trace.TagMax]int
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ndir int
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nind int
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num int
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)
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func main() {
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for b := range p9trace.FileRecords(os.Args[1:]...) {
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if ^offset == 0 {
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offset = b.Addr
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}
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if b.Addr != offset {
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fmt.Fprintf(os.Stderr, "bad address %v %v\n", offset, b.Addr)
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}
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offset++
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if b.Tag >= p9trace.TagMax {
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log.Fatal("bad tag")
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}
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count[b.Tag]++
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switch b.Tag {
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case p9trace.TagDir:
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ndir += len(b.Dir)
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case p9trace.TagInd1, p9trace.TagInd2:
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nind += len(b.Ind)
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case p9trace.TagSuper:
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if next != 0 && next != b.Addr {
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fmt.Fprintf(os.Stderr, "missing super block %v\n", next)
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}
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if last != 0 && last != b.Super.Last {
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fmt.Fprintf(os.Stderr, "bad last block %v\n", b.Addr)
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}
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fmt.Printf("super %v: cwraddr %v roraddr %v last %v next %v\n",
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b.Addr, b.Super.CWRAddr, b.Super.RORAddr,
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b.Super.Last, b.Super.Next)
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next = b.Super.Next
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last = b.Addr
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}
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num++
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}
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for i := range p9trace.TagMax {
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fmt.Fprintf(os.Stderr, "%v: %v\n", i, count[i])
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}
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fmt.Fprintf(os.Stderr, "num = %v ndir = %v nind = %v\n", num, ndir, nind)
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}

‎p9trace/super2.go‎

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// Copyright 2024 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build ignore
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// Super2 is like super but reads from an SSTable instead of raw trace files.
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package main
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import (
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"fmt"
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"log"
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"os"
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"9fans.net/go/p9trace"
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"github.com/golang/leveldb/table"
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)
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var (
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offset uint32 = ^uint32(0)
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last uint32
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next uint32
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count [p9trace.TagMax]int
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ndir int
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nind int
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num int
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)
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func main() {
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f, err := os.Open(os.Args[1])
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if err != nil {
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log.Fatal(err)
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}
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r := table.NewReader(f, nil)
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it := r.Find(nil, nil)
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for it.Next() {
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var b p9trace.Record
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if err := b.UnmarshalBinary(it.Value()); err != nil {
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log.Fatal(err)
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}
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if ^offset == 0 {
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offset = b.Addr
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}
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if b.Addr != offset {
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fmt.Fprintf(os.Stderr, "bad address %v %v\n", offset, b.Addr)
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}
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offset++
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if b.Tag >= p9trace.TagMax {
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log.Fatal("bad tag")
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}
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count[b.Tag]++
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switch b.Tag {
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case p9trace.TagDir:
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ndir += len(b.Dir)
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case p9trace.TagInd1, p9trace.TagInd2:
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nind += len(b.Ind)
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case p9trace.TagSuper:
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if next != 0 && next != b.Addr {
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fmt.Fprintf(os.Stderr, "missing super block %v\n", next)
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}
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if last != 0 && last != b.Super.Last {
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fmt.Fprintf(os.Stderr, "bad last block %v\n", b.Addr)
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}
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fmt.Printf("super %v: cwraddr %v roraddr %v last %v next %v\n",
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b.Addr, b.Super.CWRAddr, b.Super.RORAddr,
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b.Super.Last, b.Super.Next)
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next = b.Super.Next
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last = b.Addr
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}
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num++
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}
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if err := it.Close(); err != nil {
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log.Fatalf("iter: %v", err)
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}
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for i := range p9trace.TagMax {
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fmt.Fprintf(os.Stderr, "%v: %v\n", i, count[i])
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}
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fmt.Fprintf(os.Stderr, "num = %v ndir = %v nind = %v\n", num, ndir, nind)
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}

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