File size: 2,234 Bytes
e36aeda | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 | // Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package trace
import (
"fmt"
"internal/trace/tracev2"
)
// timestamp is an unprocessed timestamp.
type timestamp uint64
type batch struct {
time timestamp
gen uint64
data []byte
}
// readBatch copies b and parses the trace batch header inside.
// Returns the batch, bytes read, and an error.
func readBatch(b []byte) (batch, uint64, error) {
if len(b) == 0 {
return batch{}, 0, fmt.Errorf("batch is empty")
}
data := make([]byte, len(b))
copy(data, b)
// Read batch header byte.
if typ := tracev2.EventType(b[0]); typ == tracev2.EvEndOfGeneration {
if len(b) != 1 {
return batch{}, 1, fmt.Errorf("unexpected end of generation in batch of size >1")
}
return batch{data: data}, 1, nil
}
if typ := tracev2.EventType(b[0]); typ != tracev2.EvEventBatch && typ != tracev2.EvExperimentalBatch {
return batch{}, 1, fmt.Errorf("expected batch event, got event %d", typ)
}
total := 1
b = b[1:]
// Read the generation
gen, n, err := readUvarint(b)
if err != nil {
return batch{}, uint64(total + n), fmt.Errorf("error reading batch gen: %w", err)
}
total += n
b = b[n:]
// Read the M (discard it).
_, n, err = readUvarint(b)
if err != nil {
return batch{}, uint64(total + n), fmt.Errorf("error reading batch M ID: %w", err)
}
total += n
b = b[n:]
// Read the timestamp.
ts, n, err := readUvarint(b)
if err != nil {
return batch{}, uint64(total + n), fmt.Errorf("error reading batch timestamp: %w", err)
}
total += n
b = b[n:]
// Read the size of the batch to follow.
size, n, err := readUvarint(b)
if err != nil {
return batch{}, uint64(total + n), fmt.Errorf("error reading batch size: %w", err)
}
if size > tracev2.MaxBatchSize {
return batch{}, uint64(total + n), fmt.Errorf("invalid batch size %d, maximum is %d", size, tracev2.MaxBatchSize)
}
total += n
total += int(size)
if total != len(data) {
return batch{}, uint64(total), fmt.Errorf("expected complete batch")
}
data = data[:total]
// Return the batch.
return batch{
gen: gen,
time: timestamp(ts),
data: data,
}, uint64(total), nil
}
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