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feat: Add unit tests to reproduce buffer flush offset gaps

Phase 7: Unit Test Creation

Created comprehensive unit tests in log_buffer_flush_gap_test.go:
  - TestFlushOffsetGap_ReproduceDataLoss: Tests for gaps between disk and memory
  - TestFlushOffsetGap_CheckPrevBuffers: Tests if data stuck in prevBuffers
  - TestFlushOffsetGap_ConcurrentWriteAndFlush: Tests race conditions
  - TestFlushOffsetGap_ForceFlushAdvancesBuffer: Tests offset advancement

Initial Findings:
  - Tests run but don't reproduce exact production scenario
  - Reason: AddToBuffer doesn't auto-assign offsets (stays at 0)
  - In production: messages come with pre-assigned offsets from MQ broker
  - Need to use AddLogEntryToBuffer with explicit offsets instead

Test Structure:
  - Flush callback captures minOffset, maxOffset, buffer contents
  - Parse flushed buffers to extract actual messages
  - Compare flushed offsets vs in-memory offsets
  - Detect gaps, overlaps, and missing data

Next: Enhance tests to use explicit offset assignment to match production scenario
pull/7329/head
chrislu 3 days ago
parent
commit
f69e2a0c2d
  1. 429
      weed/util/log_buffer/log_buffer_flush_gap_test.go

429
weed/util/log_buffer/log_buffer_flush_gap_test.go

@ -0,0 +1,429 @@
package log_buffer
import (
"fmt"
"sync"
"testing"
"time"
"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
"github.com/seaweedfs/seaweedfs/weed/pb/mq_pb"
"google.golang.org/protobuf/proto"
)
// TestFlushOffsetGap_ReproduceDataLoss reproduces the critical bug where messages
// are lost in the gap between flushed disk data and in-memory buffer.
//
// OBSERVED BEHAVIOR FROM LOGS:
// Request offset: 1764
// Disk contains: 1000-1763 (764 messages)
// Memory buffer starts at: 1800
// Gap: 1764-1799 (36 messages) ← MISSING!
//
// This test verifies:
// 1. All messages sent to buffer are accounted for
// 2. No gaps exist between disk and memory offsets
// 3. Flushed data and in-memory data have continuous offset ranges
func TestFlushOffsetGap_ReproduceDataLoss(t *testing.T) {
var flushedMessages []*filer_pb.LogEntry
var flushMu sync.Mutex
flushFn := func(logBuffer *LogBuffer, startTime, stopTime time.Time, buf []byte, minOffset, maxOffset int64) {
t.Logf("FLUSH: minOffset=%d maxOffset=%d size=%d bytes", minOffset, maxOffset, len(buf))
// Parse and store flushed messages
flushMu.Lock()
defer flushMu.Unlock()
// Parse buffer to extract messages
parsedCount := 0
for pos := 0; pos+4 < len(buf); {
if pos+4 > len(buf) {
break
}
size := uint32(buf[pos])<<24 | uint32(buf[pos+1])<<16 | uint32(buf[pos+2])<<8 | uint32(buf[pos+3])
if pos+4+int(size) > len(buf) {
break
}
entryData := buf[pos+4 : pos+4+int(size)]
logEntry := &filer_pb.LogEntry{}
if err := proto.Unmarshal(entryData, logEntry); err == nil {
flushedMessages = append(flushedMessages, logEntry)
parsedCount++
}
pos += 4 + int(size)
}
t.Logf(" Parsed %d messages from flush buffer", parsedCount)
}
logBuffer := NewLogBuffer("test", 100*time.Millisecond, flushFn, nil, nil)
defer logBuffer.ShutdownLogBuffer()
// Send 100 messages
messageCount := 100
t.Logf("Sending %d messages...", messageCount)
for i := 0; i < messageCount; i++ {
logBuffer.AddToBuffer(&mq_pb.DataMessage{
Key: []byte(fmt.Sprintf("key-%d", i)),
Value: []byte(fmt.Sprintf("message-%d", i)),
TsNs: time.Now().UnixNano(),
})
}
// Force flush multiple times to simulate real workload
t.Logf("Forcing flush...")
logBuffer.ForceFlush()
// Add more messages after flush
for i := messageCount; i < messageCount+50; i++ {
logBuffer.AddToBuffer(&mq_pb.DataMessage{
Key: []byte(fmt.Sprintf("key-%d", i)),
Value: []byte(fmt.Sprintf("message-%d", i)),
TsNs: time.Now().UnixNano(),
})
}
// Force another flush
logBuffer.ForceFlush()
time.Sleep(200 * time.Millisecond) // Wait for flush to complete
// Now check the buffer state
logBuffer.RLock()
bufferStartOffset := logBuffer.bufferStartOffset
currentOffset := logBuffer.offset
pos := logBuffer.pos
logBuffer.RUnlock()
flushMu.Lock()
flushedCount := len(flushedMessages)
var maxFlushedOffset int64 = -1
var minFlushedOffset int64 = -1
if flushedCount > 0 {
minFlushedOffset = flushedMessages[0].Offset
maxFlushedOffset = flushedMessages[flushedCount-1].Offset
}
flushMu.Unlock()
t.Logf("\nBUFFER STATE AFTER FLUSH:")
t.Logf(" bufferStartOffset: %d", bufferStartOffset)
t.Logf(" currentOffset (HWM): %d", currentOffset)
t.Logf(" pos (bytes in buffer): %d", pos)
t.Logf(" Messages sent: %d (offsets 0-%d)", messageCount+50, messageCount+49)
t.Logf(" Messages flushed to disk: %d (offsets %d-%d)", flushedCount, minFlushedOffset, maxFlushedOffset)
// CRITICAL CHECK: Is there a gap between flushed data and memory buffer?
if flushedCount > 0 && maxFlushedOffset >= 0 {
gap := bufferStartOffset - (maxFlushedOffset + 1)
t.Logf("\nOFFSET CONTINUITY CHECK:")
t.Logf(" Last flushed offset: %d", maxFlushedOffset)
t.Logf(" Buffer starts at: %d", bufferStartOffset)
t.Logf(" Gap: %d offsets", gap)
if gap > 0 {
t.Errorf("❌ CRITICAL BUG REPRODUCED: OFFSET GAP DETECTED!")
t.Errorf(" Disk has offsets %d-%d", minFlushedOffset, maxFlushedOffset)
t.Errorf(" Memory buffer starts at: %d", bufferStartOffset)
t.Errorf(" MISSING OFFSETS: %d-%d (%d messages)", maxFlushedOffset+1, bufferStartOffset-1, gap)
t.Errorf(" These messages are LOST - neither on disk nor in memory!")
} else if gap < 0 {
t.Errorf("❌ OFFSET OVERLAP: Memory buffer starts BEFORE last flushed offset!")
t.Errorf(" This indicates data corruption or race condition")
} else {
t.Logf("✅ PASS: No gap detected - offsets are continuous")
}
// Check if we can read all expected offsets
t.Logf("\nREADABILITY CHECK:")
for testOffset := int64(0); testOffset < currentOffset; testOffset += 10 {
// Try to read from buffer
requestPosition := NewMessagePositionFromOffset(testOffset)
buf, _, err := logBuffer.ReadFromBuffer(requestPosition)
isReadable := (buf != nil && len(buf.Bytes()) > 0) || err == ResumeFromDiskError
status := "✅"
if !isReadable && err == nil {
status = "❌ NOT READABLE"
}
t.Logf(" Offset %d: %s (buf=%v, err=%v)", testOffset, status, buf != nil, err)
// If offset is in the gap, it should fail to read
if flushedCount > 0 && testOffset > maxFlushedOffset && testOffset < bufferStartOffset {
if isReadable {
t.Errorf(" Unexpected: Offset %d in gap range should NOT be readable!", testOffset)
} else {
t.Logf(" Expected: Offset %d in gap is not readable (data lost)", testOffset)
}
}
}
}
// Check that all sent messages are accounted for
expectedMessageCount := messageCount + 50
messagesInMemory := int(currentOffset - bufferStartOffset)
totalAccountedFor := flushedCount + messagesInMemory
t.Logf("\nMESSAGE ACCOUNTING:")
t.Logf(" Expected: %d messages", expectedMessageCount)
t.Logf(" Flushed to disk: %d", flushedCount)
t.Logf(" In memory buffer: %d (offset range %d-%d)", messagesInMemory, bufferStartOffset, currentOffset-1)
t.Logf(" Total accounted for: %d", totalAccountedFor)
t.Logf(" Missing: %d messages", expectedMessageCount-totalAccountedFor)
if totalAccountedFor < expectedMessageCount {
t.Errorf("❌ DATA LOSS CONFIRMED: %d messages are missing!", expectedMessageCount-totalAccountedFor)
} else {
t.Logf("✅ All messages accounted for")
}
}
// TestFlushOffsetGap_CheckPrevBuffers tests if messages might be stuck in prevBuffers
// instead of being properly flushed to disk.
func TestFlushOffsetGap_CheckPrevBuffers(t *testing.T) {
var flushCount int
var flushMu sync.Mutex
flushFn := func(logBuffer *LogBuffer, startTime, stopTime time.Time, buf []byte, minOffset, maxOffset int64) {
flushMu.Lock()
flushCount++
count := flushCount
flushMu.Unlock()
t.Logf("FLUSH #%d: minOffset=%d maxOffset=%d size=%d bytes", count, minOffset, maxOffset, len(buf))
}
logBuffer := NewLogBuffer("test", 100*time.Millisecond, flushFn, nil, nil)
defer logBuffer.ShutdownLogBuffer()
// Send messages in batches with flushes in between
for batch := 0; batch < 5; batch++ {
t.Logf("\nBatch %d:", batch)
// Send 20 messages
for i := 0; i < 20; i++ {
offset := int64(batch*20 + i)
logBuffer.AddToBuffer(&mq_pb.DataMessage{
Key: []byte(fmt.Sprintf("key-%d", offset)),
Value: []byte(fmt.Sprintf("message-%d", offset)),
TsNs: time.Now().UnixNano(),
})
}
// Check state before flush
logBuffer.RLock()
beforeFlushOffset := logBuffer.offset
beforeFlushStart := logBuffer.bufferStartOffset
logBuffer.RUnlock()
// Force flush
logBuffer.ForceFlush()
time.Sleep(50 * time.Millisecond)
// Check state after flush
logBuffer.RLock()
afterFlushOffset := logBuffer.offset
afterFlushStart := logBuffer.bufferStartOffset
prevBufferCount := len(logBuffer.prevBuffers.buffers)
// Check prevBuffers state
t.Logf(" Before flush: offset=%d, bufferStartOffset=%d", beforeFlushOffset, beforeFlushStart)
t.Logf(" After flush: offset=%d, bufferStartOffset=%d, prevBuffers=%d",
afterFlushOffset, afterFlushStart, prevBufferCount)
// Check each prevBuffer
for i, prevBuf := range logBuffer.prevBuffers.buffers {
if prevBuf.size > 0 {
t.Logf(" prevBuffer[%d]: offsets %d-%d, size=%d bytes (NOT FLUSHED!)",
i, prevBuf.startOffset, prevBuf.offset, prevBuf.size)
}
}
logBuffer.RUnlock()
// CRITICAL: Check if bufferStartOffset advanced correctly
expectedNewStart := beforeFlushOffset
if afterFlushStart != expectedNewStart {
t.Errorf(" ❌ bufferStartOffset mismatch!")
t.Errorf(" Expected: %d (= offset before flush)", expectedNewStart)
t.Errorf(" Actual: %d", afterFlushStart)
t.Errorf(" Gap: %d offsets", expectedNewStart-afterFlushStart)
}
}
}
// TestFlushOffsetGap_ConcurrentWriteAndFlush tests for race conditions
// between writing new messages and flushing old ones.
func TestFlushOffsetGap_ConcurrentWriteAndFlush(t *testing.T) {
var allFlushedOffsets []int64
var flushMu sync.Mutex
flushFn := func(logBuffer *LogBuffer, startTime, stopTime time.Time, buf []byte, minOffset, maxOffset int64) {
t.Logf("FLUSH: offsets %d-%d (%d bytes)", minOffset, maxOffset, len(buf))
flushMu.Lock()
// Record the offset range that was flushed
for offset := minOffset; offset <= maxOffset; offset++ {
allFlushedOffsets = append(allFlushedOffsets, offset)
}
flushMu.Unlock()
}
logBuffer := NewLogBuffer("test", 50*time.Millisecond, flushFn, nil, nil)
defer logBuffer.ShutdownLogBuffer()
// Concurrently write messages and force flushes
var wg sync.WaitGroup
// Writer goroutine
wg.Add(1)
go func() {
defer wg.Done()
for i := 0; i < 200; i++ {
logBuffer.AddToBuffer(&mq_pb.DataMessage{
Key: []byte(fmt.Sprintf("key-%d", i)),
Value: []byte(fmt.Sprintf("message-%d", i)),
TsNs: time.Now().UnixNano(),
})
if i%50 == 0 {
time.Sleep(10 * time.Millisecond)
}
}
}()
// Flusher goroutine
wg.Add(1)
go func() {
defer wg.Done()
for i := 0; i < 5; i++ {
time.Sleep(30 * time.Millisecond)
logBuffer.ForceFlush()
}
}()
wg.Wait()
time.Sleep(200 * time.Millisecond) // Wait for final flush
// Check final state
logBuffer.RLock()
finalOffset := logBuffer.offset
finalBufferStart := logBuffer.bufferStartOffset
logBuffer.RUnlock()
flushMu.Lock()
flushedCount := len(allFlushedOffsets)
flushMu.Unlock()
expectedCount := int(finalOffset)
inMemory := int(finalOffset - finalBufferStart)
totalAccountedFor := flushedCount + inMemory
t.Logf("\nFINAL STATE:")
t.Logf(" Total messages sent: %d (offsets 0-%d)", expectedCount, expectedCount-1)
t.Logf(" Flushed to disk: %d", flushedCount)
t.Logf(" In memory: %d (offsets %d-%d)", inMemory, finalBufferStart, finalOffset-1)
t.Logf(" Total accounted: %d", totalAccountedFor)
t.Logf(" Missing: %d", expectedCount-totalAccountedFor)
if totalAccountedFor < expectedCount {
t.Errorf("❌ DATA LOSS in concurrent scenario: %d messages missing!", expectedCount-totalAccountedFor)
}
}
// TestFlushOffsetGap_ForceFlushAdvancesBuffer tests if ForceFlush
// properly advances bufferStartOffset after flushing.
func TestFlushOffsetGap_ForceFlushAdvancesBuffer(t *testing.T) {
flushedRanges := []struct{ min, max int64 }{}
var flushMu sync.Mutex
flushFn := func(logBuffer *LogBuffer, startTime, stopTime time.Time, buf []byte, minOffset, maxOffset int64) {
flushMu.Lock()
flushedRanges = append(flushedRanges, struct{ min, max int64 }{minOffset, maxOffset})
flushMu.Unlock()
t.Logf("FLUSH: offsets %d-%d", minOffset, maxOffset)
}
logBuffer := NewLogBuffer("test", time.Hour, flushFn, nil, nil) // Long interval, manual flush only
defer logBuffer.ShutdownLogBuffer()
// Send messages, flush, check state - repeat
for round := 0; round < 3; round++ {
t.Logf("\n=== ROUND %d ===", round)
// Check state before adding messages
logBuffer.RLock()
beforeOffset := logBuffer.offset
beforeStart := logBuffer.bufferStartOffset
logBuffer.RUnlock()
t.Logf("Before adding: offset=%d, bufferStartOffset=%d", beforeOffset, beforeStart)
// Add 10 messages
for i := 0; i < 10; i++ {
logBuffer.AddToBuffer(&mq_pb.DataMessage{
Key: []byte(fmt.Sprintf("round-%d-msg-%d", round, i)),
Value: []byte(fmt.Sprintf("data-%d-%d", round, i)),
TsNs: time.Now().UnixNano(),
})
}
// Check state after adding
logBuffer.RLock()
afterAddOffset := logBuffer.offset
afterAddStart := logBuffer.bufferStartOffset
logBuffer.RUnlock()
t.Logf("After adding: offset=%d, bufferStartOffset=%d", afterAddOffset, afterAddStart)
// Force flush
t.Logf("Forcing flush...")
logBuffer.ForceFlush()
time.Sleep(100 * time.Millisecond)
// Check state after flush
logBuffer.RLock()
afterFlushOffset := logBuffer.offset
afterFlushStart := logBuffer.bufferStartOffset
logBuffer.RUnlock()
t.Logf("After flush: offset=%d, bufferStartOffset=%d", afterFlushOffset, afterFlushStart)
// CRITICAL CHECK: bufferStartOffset should advance to where offset was before flush
if afterFlushStart != afterAddOffset {
t.Errorf("❌ FLUSH BUG: bufferStartOffset did NOT advance correctly!")
t.Errorf(" Expected bufferStartOffset=%d (= offset after add)", afterAddOffset)
t.Errorf(" Actual bufferStartOffset=%d", afterFlushStart)
t.Errorf(" Gap: %d offsets WILL BE LOST", afterAddOffset-afterFlushStart)
} else {
t.Logf("✅ bufferStartOffset correctly advanced to %d", afterFlushStart)
}
}
// Final verification: check all offset ranges are continuous
flushMu.Lock()
t.Logf("\n=== FLUSHED RANGES ===")
for i, r := range flushedRanges {
t.Logf("Flush #%d: offsets %d-%d", i, r.min, r.max)
// Check continuity with previous flush
if i > 0 {
prevMax := flushedRanges[i-1].max
currentMin := r.min
gap := currentMin - (prevMax + 1)
if gap > 0 {
t.Errorf("❌ GAP between flush #%d and #%d: %d offsets missing!", i-1, i, gap)
} else if gap < 0 {
t.Errorf("❌ OVERLAP between flush #%d and #%d: %d offsets duplicated!", i-1, i, -gap)
} else {
t.Logf(" ✅ Continuous with previous flush")
}
}
}
flushMu.Unlock()
}
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