Files
imgproxy/asyncbuffer/buffer_test.go
2025-07-31 18:18:13 +02:00

362 lines
11 KiB
Go

package asyncbuffer
import (
"bytes"
"crypto/rand"
"errors"
"io"
"os"
"sync"
"sync/atomic"
"testing"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
const (
halfChunkSize = ChunkSize / 2
quaterChunkSize = ChunkSize / 4
)
// erraticReader is a test reader that simulates a slow read and can fail after reading a certain number of bytes
type erraticReader struct {
reader bytes.Reader
failAt int64 // if set, will return an error after reading this many bytes
}
// Read reads data from the testReader, simulating a slow read and a potential failure
func (r *erraticReader) Read(p []byte) (n int, err error) {
cur, _ := r.reader.Seek(0, io.SeekCurrent)
if r.failAt > 0 && r.failAt < cur+int64(len(p)) {
return 0, errors.New("simulated read failure")
}
return r.reader.Read(p)
}
// blockingReader is a test reader which flushes data in chunks
type blockingReader struct {
reader bytes.Reader
mu sync.Mutex // locked reader does not return anything
unlocking atomic.Bool // if true, will proceed without locking each chunk
}
// newBlockingReader creates a new partialReader in locked state
func newBlockingReader(reader bytes.Reader) *blockingReader {
r := &blockingReader{
reader: reader,
}
r.mu.Lock()
return r
}
// flushNextChunk unlocks the reader, allowing it to return the next chunk of data
func (r *blockingReader) flushNextChunk() {
r.mu.Unlock()
}
// flush unlocks the reader, allowing it to return all data as usual
func (r *blockingReader) flush() {
r.unlocking.Store(true) // allow reading data without blocking
r.mu.Unlock() // and continue
}
// Read reads data from the testReader, simulating a slow read and a potential failure
func (r *blockingReader) Read(p []byte) (n int, err error) {
if !r.unlocking.Load() {
r.mu.Lock()
}
n, err = r.reader.Read(p)
return n, err
}
// generateSourceData generates a byte slice with 4.5 chunks of data
func generateSourceData(t *testing.T, size int64) ([]byte, *bytes.Reader) {
// We use small chunks for tests, let's check the ChunkSize just in case
assert.GreaterOrEqual(t, ChunkSize, 20, "ChunkSize required for tests must be greater than 10 bytes")
// Create a byte slice with 4 chunks of ChunkSize
source := make([]byte, size)
// Fill the source with random data
_, err := rand.Read(source)
require.NoError(t, err)
return source, bytes.NewReader(source)
}
// TestAsyncBufferRead tests reading from AsyncBuffer using readAt method which is base for all other methods
func TestAsyncBufferReadAt(t *testing.T) {
// Let's use source buffer which is 4.5 chunks long
source, bytesReader := generateSourceData(t, int64(ChunkSize*4)+halfChunkSize)
asyncBuffer := FromReader(bytesReader)
defer asyncBuffer.Close()
asyncBuffer.Wait() // Wait for all chunks to be read since we're going to read all data
// Let's read all the data
target := make([]byte, len(source))
n, err := asyncBuffer.readAt(target, 0)
require.NoError(t, err)
assert.Equal(t, len(source), n)
assert.Equal(t, target, source)
// Let's read all the data + a bit more
target = make([]byte, len(source)+1)
n, err = asyncBuffer.readAt(target, 0)
require.ErrorIs(t, err, io.EOF) // We read all the data, and reached end
assert.Equal(t, len(source), n)
assert.Equal(t, target[:n], source)
// Let's read > 1 chunk, but with offset from the beginning and the end
target = make([]byte, len(source)-halfChunkSize)
n, err = asyncBuffer.readAt(target, quaterChunkSize)
require.NoError(t, err)
assert.Equal(t, len(target), n)
assert.Equal(t, target, source[quaterChunkSize:len(source)-quaterChunkSize])
// Let's read some data from the middle of the stream < chunk size
target = make([]byte, ChunkSize/4)
n, err = asyncBuffer.readAt(target, ChunkSize+ChunkSize/4)
require.NoError(t, err)
assert.Equal(t, quaterChunkSize, n)
assert.Equal(t, target, source[ChunkSize+quaterChunkSize:ChunkSize+quaterChunkSize*2])
// Let's read some data from the latest half chunk
target = make([]byte, quaterChunkSize)
n, err = asyncBuffer.readAt(target, ChunkSize*4+quaterChunkSize)
require.NoError(t, err)
assert.Equal(t, quaterChunkSize, n)
assert.Equal(t, target, source[ChunkSize*4+quaterChunkSize:ChunkSize*4+halfChunkSize])
// Let's try to read more data then available in the stream
target = make([]byte, ChunkSize*2)
n, err = asyncBuffer.readAt(target, ChunkSize*4)
require.Error(t, err)
assert.Equal(t, err, io.EOF)
assert.Equal(t, ChunkSize/2, n)
assert.Equal(t, target[:ChunkSize/2], source[ChunkSize*4:]) // We read only last half chunk
// Let's try to read data beyond the end of the stream
target = make([]byte, ChunkSize*2)
n, err = asyncBuffer.readAt(target, ChunkSize*5)
require.Error(t, err)
assert.Equal(t, err, io.EOF)
assert.Equal(t, 0, n)
}
// TestAsyncBufferRead tests reading from AsyncBuffer using ReadAt method
func TestAsyncBufferReadAtSmallBuffer(t *testing.T) {
source, bytesReader := generateSourceData(t, 20)
asyncBuffer := FromReader(bytesReader)
defer asyncBuffer.Close()
// First, let's read all the data
target := make([]byte, len(source))
n, err := asyncBuffer.readAt(target, 0)
require.NoError(t, err)
assert.Equal(t, len(source), n)
assert.Equal(t, target, source)
// Let's read some data
target = make([]byte, 2)
n, err = asyncBuffer.readAt(target, 1)
require.NoError(t, err)
assert.Equal(t, len(target), n)
assert.Equal(t, target, source[1:3])
// Let's read some data beyond the end of the stream
target = make([]byte, 2)
n, err = asyncBuffer.readAt(target, 50)
require.Error(t, err)
assert.Equal(t, err, io.EOF)
assert.Equal(t, 0, n)
}
func TestAsyncBufferReader(t *testing.T) {
source, bytesReader := generateSourceData(t, int64(ChunkSize*4)+halfChunkSize)
// Create an AsyncBuffer with the byte slice
asyncBuffer := FromReader(bytesReader)
defer asyncBuffer.Close()
// Let's wait for all chunks to be read
size, err := asyncBuffer.Wait()
require.NoError(t, err, "AsyncBuffer failed to wait for all chunks")
assert.Equal(t, int64(ChunkSize*4+halfChunkSize), size)
reader := asyncBuffer.Reader()
// Ensure the total length of the data is ChunkSize*4
require.NoError(t, err)
// Read the first two chunks
twoChunks := make([]byte, ChunkSize*2)
n, err := reader.Read(twoChunks)
require.NoError(t, err)
assert.Equal(t, ChunkSize*2, n)
assert.Equal(t, source[:ChunkSize*2], twoChunks)
// Seek to the last chunk + 10 bytes
pos, err := reader.Seek(ChunkSize*3+5, io.SeekStart)
require.NoError(t, err)
assert.Equal(t, int64(ChunkSize*3+5), pos)
// Read the next 10 bytes
smallSlice := make([]byte, 10)
n, err = reader.Read(smallSlice)
require.NoError(t, err)
assert.Equal(t, 10, n)
assert.Equal(t, source[ChunkSize*3+5:ChunkSize*3+5+10], smallSlice)
// Seek -10 bytes from the current position
pos, err = reader.Seek(-10, io.SeekCurrent)
require.NoError(t, err)
assert.Equal(t, int64(ChunkSize*3+5), pos)
// Read data again
n, err = reader.Read(smallSlice)
require.NoError(t, err)
assert.Equal(t, 10, n)
assert.Equal(t, source[ChunkSize*3+5:ChunkSize*3+5+10], smallSlice)
// Seek -10 bytes from end of the stream
pos, err = reader.Seek(-10, io.SeekEnd)
require.NoError(t, err)
assert.Equal(t, size-10, pos)
// Read last 10 bytes
n, err = reader.Read(smallSlice)
require.NoError(t, err)
assert.Equal(t, 10, n)
assert.Equal(t, source[size-10:], smallSlice)
// Seek beyond the end of the stream and try to read
pos, err = reader.Seek(1024, io.SeekCurrent)
require.NoError(t, err)
assert.Equal(t, size+1024, pos)
_, err = reader.Read(smallSlice)
require.ErrorIs(t, err, io.EOF)
}
// TestAsyncBufferClose tests closing the AsyncBuffer
func TestAsyncBufferClose(t *testing.T) {
_, bytesReader := generateSourceData(t, int64(ChunkSize*4)+halfChunkSize)
// Create an AsyncBuffer with the byte slice
asyncBuffer := FromReader(bytesReader)
reader1 := asyncBuffer.Reader()
reader2 := asyncBuffer.Reader()
asyncBuffer.Close()
b := make([]byte, 10)
_, err := reader1.Read(b)
require.Error(t, err, "asyncbuffer.AsyncBuffer.ReadAt: attempt to read on closed reader")
_, err = reader2.Read(b)
require.Error(t, err, "asyncbuffer.AsyncBuffer.ReadAt: attempt to read on closed reader")
// After closing the closed reader, it should not panic
asyncBuffer.Close()
_, err = reader2.Read(b)
require.Error(t, err, "asyncbuffer.AsyncBuffer.ReadAt: attempt to read on closed reader")
}
// TestAsyncBufferReadAtErrAtSomePoint tests reading from AsyncBuffer using readAt method
// which would fail somewhere
func TestAsyncBufferReadAtErrAtSomePoint(t *testing.T) {
// Let's use source buffer which is 4.5 chunks long
source, bytesReader := generateSourceData(t, int64(ChunkSize*4)+halfChunkSize)
slowReader := &erraticReader{reader: *bytesReader, failAt: ChunkSize*3 + 5} // fails at last chunk
asyncBuffer := FromReader(slowReader)
defer asyncBuffer.Close()
// Let's wait for all chunks to be read
_, err := asyncBuffer.Wait()
require.Error(t, err, "simulated read failure")
// Let's read something, but before error occurs
target := make([]byte, halfChunkSize)
n, err := asyncBuffer.readAt(target, 0)
require.NoError(t, err)
assert.Equal(t, len(target), n)
assert.Equal(t, target, source[:halfChunkSize])
// And again
target = make([]byte, halfChunkSize)
n, err = asyncBuffer.readAt(target, halfChunkSize)
require.NoError(t, err)
assert.Equal(t, len(target), n)
assert.Equal(t, target, source[halfChunkSize:halfChunkSize*2])
// Let's read something, but when error occurs
target = make([]byte, halfChunkSize)
_, err = asyncBuffer.readAt(target, ChunkSize*3)
require.Error(t, err, "simulated read failure")
}
// TestAsyncBufferReadAsync tests reading from AsyncBuffer using readAt method
// with full = false
func TestAsyncBufferReadAsync(t *testing.T) {
// Let's use source buffer which is 4.5 chunks long
source, bytesReader := generateSourceData(t, int64(ChunkSize)*3)
blockingReader := newBlockingReader(*bytesReader)
asyncBuffer := FromReader(blockingReader)
defer asyncBuffer.Close()
// flush the first chunk to allow reading
blockingReader.flushNextChunk()
// Let's try to read first two chunks, however,
// we know that only the first chunk is available
target := make([]byte, ChunkSize*2)
n, err := asyncBuffer.readAt(target, 0)
require.NoError(t, err)
assert.Equal(t, ChunkSize, n)
assert.Equal(t, target[:ChunkSize], source[:ChunkSize])
blockingReader.flushNextChunk() // unlock reader to allow read second chunk
asyncBuffer.WaitFor(ChunkSize + 1) // wait for the second chunk to be available
target = make([]byte, ChunkSize*2)
n, err = asyncBuffer.readAt(target, 0)
require.NoError(t, err)
assert.Equal(t, ChunkSize*2, n)
assert.Equal(t, target, source[:ChunkSize*2])
blockingReader.flush() // Flush the rest of the data
asyncBuffer.Wait()
// Try to read near end of the stream, EOF
target = make([]byte, ChunkSize)
n, err = asyncBuffer.readAt(target, ChunkSize*3-1)
require.ErrorIs(t, err, io.EOF)
assert.Equal(t, 1, n)
assert.Equal(t, target[0], source[ChunkSize*3-1])
// Try to read beyond the end of the stream == eof
target = make([]byte, ChunkSize)
n, err = asyncBuffer.readAt(target, ChunkSize*3)
require.ErrorIs(t, io.EOF, err)
assert.Equal(t, 0, n)
}
// TestAsyncBufferReadAllCompability tests that ReadAll methods works as expected
func TestAsyncBufferReadAllCompability(t *testing.T) {
source, err := os.ReadFile("../testdata/test1.jpg")
require.NoError(t, err)
asyncBuffer := FromReader(bytes.NewReader(source))
defer asyncBuffer.Close()
b, err := io.ReadAll(asyncBuffer.Reader())
require.NoError(t, err)
require.Len(t, b, len(source))
}