skia2/tests/FrontBufferedStreamTest.cpp

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/*
* Copyright 2013 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkFrontBufferedStream.h"
#include "SkRefCnt.h"
#include "SkStream.h"
#include "SkTypes.h"
#include "Test.h"
static void test_read(skiatest::Reporter* reporter, SkStream* bufferedStream,
const void* expectations, size_t bytesToRead) {
// output for reading bufferedStream.
SkAutoMalloc storage(bytesToRead);
const size_t bytesRead = bufferedStream->read(storage.get(), bytesToRead);
REPORTER_ASSERT(reporter, bytesRead == bytesToRead || bufferedStream->isAtEnd());
REPORTER_ASSERT(reporter, memcmp(storage.get(), expectations, bytesRead) == 0);
}
static void test_rewind(skiatest::Reporter* reporter,
SkStream* bufferedStream, bool shouldSucceed) {
const bool success = bufferedStream->rewind();
REPORTER_ASSERT(reporter, success == shouldSucceed);
}
// Test that hasLength() returns the correct value, based on the stream
// being wrapped. A length can only be known if the wrapped stream has a
// length and it has a position (so its initial position can be taken into
// account when computing the length).
static void test_hasLength(skiatest::Reporter* reporter,
const SkStream& bufferedStream,
const SkStream& streamBeingBuffered) {
if (streamBeingBuffered.hasLength() && streamBeingBuffered.hasPosition()) {
REPORTER_ASSERT(reporter, bufferedStream.hasLength());
} else {
REPORTER_ASSERT(reporter, !bufferedStream.hasLength());
}
}
// All tests will buffer this string, and compare output to the original.
// The string is long to ensure that all of our lengths being tested are
// smaller than the string length.
const char gAbcs[] = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwx";
// Tests reading the stream across boundaries of what has been buffered so far and what
// the total buffer size is.
static void test_incremental_buffering(skiatest::Reporter* reporter, size_t bufferSize) {
SkMemoryStream memStream(gAbcs, strlen(gAbcs), false);
SkAutoTUnref<SkStream> bufferedStream(SkFrontBufferedStream::Create(&memStream, bufferSize));
test_hasLength(reporter, *bufferedStream.get(), memStream);
// First, test reading less than the max buffer size.
test_read(reporter, bufferedStream, gAbcs, bufferSize / 2);
// Now test rewinding back to the beginning and reading less than what was
// already buffered.
test_rewind(reporter, bufferedStream, true);
test_read(reporter, bufferedStream, gAbcs, bufferSize / 4);
// Now test reading part of what was buffered, and buffering new data.
test_read(reporter, bufferedStream, gAbcs + bufferedStream->getPosition(), bufferSize / 2);
// Now test reading what was buffered, buffering new data, and
// reading directly from the stream.
test_rewind(reporter, bufferedStream, true);
test_read(reporter, bufferedStream, gAbcs, bufferSize << 1);
// We have reached the end of the buffer, so rewinding will fail.
// This test assumes that the stream is larger than the buffer; otherwise the
// result of rewind should be true.
test_rewind(reporter, bufferedStream, false);
}
static void test_perfectly_sized_buffer(skiatest::Reporter* reporter, size_t bufferSize) {
SkMemoryStream memStream(gAbcs, strlen(gAbcs), false);
SkAutoTUnref<SkStream> bufferedStream(SkFrontBufferedStream::Create(&memStream, bufferSize));
test_hasLength(reporter, *bufferedStream.get(), memStream);
// Read exactly the amount that fits in the buffer.
test_read(reporter, bufferedStream, gAbcs, bufferSize);
// Rewinding should succeed.
test_rewind(reporter, bufferedStream, true);
// Once again reading buffered info should succeed
test_read(reporter, bufferedStream, gAbcs, bufferSize);
// Read past the size of the buffer. At this point, we cannot return.
test_read(reporter, bufferedStream, gAbcs + bufferedStream->getPosition(), 1);
test_rewind(reporter, bufferedStream, false);
}
static void test_skipping(skiatest::Reporter* reporter, size_t bufferSize) {
SkMemoryStream memStream(gAbcs, strlen(gAbcs), false);
SkAutoTUnref<SkStream> bufferedStream(SkFrontBufferedStream::Create(&memStream, bufferSize));
test_hasLength(reporter, *bufferedStream.get(), memStream);
// Skip half the buffer.
bufferedStream->skip(bufferSize / 2);
// Rewind, then read part of the buffer, which should have been read.
test_rewind(reporter, bufferedStream, true);
test_read(reporter, bufferedStream, gAbcs, bufferSize / 4);
// Now skip beyond the buffered piece, but still within the total buffer.
bufferedStream->skip(bufferSize / 2);
// Test that reading will still work.
test_read(reporter, bufferedStream, gAbcs + bufferedStream->getPosition(), bufferSize / 4);
test_rewind(reporter, bufferedStream, true);
test_read(reporter, bufferedStream, gAbcs, bufferSize);
}
// A custom class whose isAtEnd behaves the way Android's stream does - since it is an adaptor to a
// Java InputStream, it does not know that it is at the end until it has attempted to read beyond
// the end and failed. Used by test_read_beyond_buffer.
class AndroidLikeMemoryStream : public SkMemoryStream {
public:
AndroidLikeMemoryStream(void* data, size_t size, bool ownMemory)
: INHERITED(data, size, ownMemory)
, fIsAtEnd(false) {}
size_t read(void* dst, size_t requested) SK_OVERRIDE {
size_t bytesRead = this->INHERITED::read(dst, requested);
if (bytesRead < requested) {
fIsAtEnd = true;
}
return bytesRead;
}
bool isAtEnd() const SK_OVERRIDE {
return fIsAtEnd;
}
private:
bool fIsAtEnd;
typedef SkMemoryStream INHERITED;
};
// This test ensures that buffering the exact length of the stream and attempting to read beyond it
// does not invalidate the buffer.
static void test_read_beyond_buffer(skiatest::Reporter* reporter, size_t bufferSize) {
// Use a stream that behaves like Android's stream.
AndroidLikeMemoryStream memStream((void*)gAbcs, bufferSize, false);
// Create a buffer that matches the length of the stream.
SkAutoTUnref<SkStream> bufferedStream(SkFrontBufferedStream::Create(&memStream, bufferSize));
test_hasLength(reporter, *bufferedStream.get(), memStream);
// Attempt to read one more than the bufferSize
test_read(reporter, bufferedStream.get(), gAbcs, bufferSize + 1);
test_rewind(reporter, bufferedStream.get(), true);
// Ensure that the initial read did not invalidate the buffer.
test_read(reporter, bufferedStream, gAbcs, bufferSize);
}
// Dummy stream that optionally has a length and/or position. Tests that FrontBufferedStream's
// length depends on the stream it's buffering having a length and position.
class LengthOptionalStream : public SkStream {
public:
LengthOptionalStream(bool hasLength, bool hasPosition)
: fHasLength(hasLength)
, fHasPosition(hasPosition)
{}
virtual bool hasLength() const SK_OVERRIDE {
return fHasLength;
}
virtual bool hasPosition() const SK_OVERRIDE {
return fHasPosition;
}
virtual size_t read(void*, size_t) SK_OVERRIDE {
return 0;
}
virtual bool isAtEnd() const SK_OVERRIDE {
return true;
}
private:
const bool fHasLength;
const bool fHasPosition;
};
// Test all possible combinations of the wrapped stream having a length and a position.
static void test_length_combos(skiatest::Reporter* reporter, size_t bufferSize) {
for (int hasLen = 0; hasLen <= 1; hasLen++) {
for (int hasPos = 0; hasPos <= 1; hasPos++) {
LengthOptionalStream stream(SkToBool(hasLen), SkToBool(hasPos));
SkAutoTUnref<SkStream> buffered(SkFrontBufferedStream::Create(&stream, bufferSize));
test_hasLength(reporter, *buffered.get(), stream);
}
}
}
// Test using a stream with an initial offset.
static void test_initial_offset(skiatest::Reporter* reporter, size_t bufferSize) {
SkMemoryStream memStream(gAbcs, strlen(gAbcs), false);
// Skip a few characters into the memStream, so that bufferedStream represents an offset into
// the stream it wraps.
const size_t arbitraryOffset = 17;
memStream.skip(arbitraryOffset);
SkAutoTUnref<SkStream> bufferedStream(SkFrontBufferedStream::Create(&memStream, bufferSize));
// Since SkMemoryStream has a length and a position, bufferedStream must also.
REPORTER_ASSERT(reporter, bufferedStream->hasLength());
const size_t amountToRead = 10;
const size_t bufferedLength = bufferedStream->getLength();
size_t currentPosition = bufferedStream->getPosition();
REPORTER_ASSERT(reporter, 0 == currentPosition);
// Read the stream in chunks. After each read, the position must match currentPosition,
// which sums the amount attempted to read, unless the end of the stream has been reached.
// Importantly, the end should not have been reached until currentPosition == bufferedLength.
while (currentPosition < bufferedLength) {
REPORTER_ASSERT(reporter, !bufferedStream->isAtEnd());
test_read(reporter, bufferedStream, gAbcs + arbitraryOffset + currentPosition,
amountToRead);
currentPosition = SkTMin(currentPosition + amountToRead, bufferedLength);
REPORTER_ASSERT(reporter, bufferedStream->getPosition() == currentPosition);
}
REPORTER_ASSERT(reporter, bufferedStream->isAtEnd());
REPORTER_ASSERT(reporter, bufferedLength == currentPosition);
}
static void test_buffers(skiatest::Reporter* reporter, size_t bufferSize) {
test_incremental_buffering(reporter, bufferSize);
test_perfectly_sized_buffer(reporter, bufferSize);
test_skipping(reporter, bufferSize);
test_read_beyond_buffer(reporter, bufferSize);
test_length_combos(reporter, bufferSize);
test_initial_offset(reporter, bufferSize);
}
DEF_TEST(FrontBufferedStream, reporter) {
// Test 6 and 64, which are used by Android, as well as another arbitrary length.
test_buffers(reporter, 6);
test_buffers(reporter, 15);
test_buffers(reporter, 64);
}