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      1 /*
      2  * libjingle
      3  * Copyright 2004--2011, Google Inc.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are met:
      7  *
      8  *  1. Redistributions of source code must retain the above copyright notice,
      9  *     this list of conditions and the following disclaimer.
     10  *  2. Redistributions in binary form must reproduce the above copyright notice,
     11  *     this list of conditions and the following disclaimer in the documentation
     12  *     and/or other materials provided with the distribution.
     13  *  3. The name of the author may not be used to endorse or promote products
     14  *     derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #include "talk/base/gunit.h"
     29 #include "talk/base/stream.h"
     30 
     31 namespace talk_base {
     32 
     33 ///////////////////////////////////////////////////////////////////////////////
     34 // TestStream
     35 ///////////////////////////////////////////////////////////////////////////////
     36 
     37 class TestStream : public StreamInterface {
     38  public:
     39   TestStream() : pos_(0) { }
     40 
     41   virtual StreamState GetState() const { return SS_OPEN; }
     42   virtual StreamResult Read(void* buffer, size_t buffer_len,
     43                             size_t* read, int* error) {
     44     unsigned char* uc_buffer = static_cast<unsigned char*>(buffer);
     45     for (size_t i = 0; i < buffer_len; ++i) {
     46       uc_buffer[i] = static_cast<unsigned char>(pos_++);
     47     }
     48     if (read)
     49       *read = buffer_len;
     50     return SR_SUCCESS;
     51   }
     52   virtual StreamResult Write(const void* data, size_t data_len,
     53                              size_t* written, int* error) {
     54     if (error)
     55       *error = -1;
     56     return SR_ERROR;
     57   }
     58   virtual void Close() { }
     59   virtual bool SetPosition(size_t position) {
     60     pos_ = position;
     61     return true;
     62   }
     63   virtual bool GetPosition(size_t* position) const {
     64     if (position) *position = pos_;
     65     return true;
     66   }
     67   virtual bool GetSize(size_t* size) const {
     68     return false;
     69   }
     70   virtual bool GetAvailable(size_t* size) const {
     71     return false;
     72   }
     73 
     74  private:
     75   size_t pos_;
     76 };
     77 
     78 bool VerifyTestBuffer(unsigned char* buffer, size_t len,
     79                       unsigned char value) {
     80   bool passed = true;
     81   for (size_t i = 0; i < len; ++i) {
     82     if (buffer[i] != value++) {
     83       passed = false;
     84       break;
     85     }
     86   }
     87   // Ensure that we don't pass again without re-writing
     88   memset(buffer, 0, len);
     89   return passed;
     90 }
     91 
     92 void SeekTest(StreamInterface* stream, const unsigned char value) {
     93   size_t bytes;
     94   unsigned char buffer[13] = { 0 };
     95   const size_t kBufSize = sizeof(buffer);
     96 
     97   EXPECT_EQ(stream->Read(buffer, kBufSize, &bytes, NULL), SR_SUCCESS);
     98   EXPECT_EQ(bytes, kBufSize);
     99   EXPECT_TRUE(VerifyTestBuffer(buffer, kBufSize, value));
    100   EXPECT_TRUE(stream->GetPosition(&bytes));
    101   EXPECT_EQ(13U, bytes);
    102 
    103   EXPECT_TRUE(stream->SetPosition(7));
    104 
    105   EXPECT_EQ(stream->Read(buffer, kBufSize, &bytes, NULL), SR_SUCCESS);
    106   EXPECT_EQ(bytes, kBufSize);
    107   EXPECT_TRUE(VerifyTestBuffer(buffer, kBufSize, value + 7));
    108   EXPECT_TRUE(stream->GetPosition(&bytes));
    109   EXPECT_EQ(20U, bytes);
    110 }
    111 
    112 TEST(StreamSegment, TranslatesPosition) {
    113   TestStream* test = new TestStream;
    114   // Verify behavior of original stream
    115   SeekTest(test, 0);
    116   StreamSegment* segment = new StreamSegment(test);
    117   // Verify behavior of adapted stream (all values offset by 20)
    118   SeekTest(segment, 20);
    119   delete segment;
    120 }
    121 
    122 TEST(StreamSegment, SupportsArtificialTermination) {
    123   TestStream* test = new TestStream;
    124 
    125   size_t bytes;
    126   unsigned char buffer[5000] = { 0 };
    127   const size_t kBufSize = sizeof(buffer);
    128 
    129   {
    130     StreamInterface* stream = test;
    131 
    132     // Read a lot of bytes
    133     EXPECT_EQ(stream->Read(buffer, kBufSize, &bytes, NULL), SR_SUCCESS);
    134     EXPECT_EQ(bytes, kBufSize);
    135     EXPECT_TRUE(VerifyTestBuffer(buffer, kBufSize, 0));
    136 
    137     // Test seeking far ahead
    138     EXPECT_TRUE(stream->SetPosition(12345));
    139 
    140     // Read a bunch more bytes
    141     EXPECT_EQ(stream->Read(buffer, kBufSize, &bytes, NULL), SR_SUCCESS);
    142     EXPECT_EQ(bytes, kBufSize);
    143     EXPECT_TRUE(VerifyTestBuffer(buffer, kBufSize, 12345 % 256));
    144   }
    145 
    146   // Create a segment of test stream in range [100,600)
    147   EXPECT_TRUE(test->SetPosition(100));
    148   StreamSegment* segment = new StreamSegment(test, 500);
    149 
    150   {
    151     StreamInterface* stream = segment;
    152 
    153     EXPECT_EQ(stream->Read(buffer, kBufSize, &bytes, NULL), SR_SUCCESS);
    154     EXPECT_EQ(500U, bytes);
    155     EXPECT_TRUE(VerifyTestBuffer(buffer, 500, 100));
    156     EXPECT_EQ(stream->Read(buffer, kBufSize, &bytes, NULL), SR_EOS);
    157 
    158     // Test seeking past "end" of stream
    159     EXPECT_FALSE(stream->SetPosition(12345));
    160     EXPECT_FALSE(stream->SetPosition(501));
    161 
    162     // Test seeking to end (edge case)
    163     EXPECT_TRUE(stream->SetPosition(500));
    164     EXPECT_EQ(stream->Read(buffer, kBufSize, &bytes, NULL), SR_EOS);
    165 
    166     // Test seeking to start
    167     EXPECT_TRUE(stream->SetPosition(0));
    168     EXPECT_EQ(stream->Read(buffer, kBufSize, &bytes, NULL), SR_SUCCESS);
    169     EXPECT_EQ(500U, bytes);
    170     EXPECT_TRUE(VerifyTestBuffer(buffer, 500, 100));
    171     EXPECT_EQ(stream->Read(buffer, kBufSize, &bytes, NULL), SR_EOS);
    172   }
    173 
    174   delete segment;
    175 }
    176 
    177 TEST(FifoBufferTest, TestAll) {
    178   const size_t kSize = 16;
    179   const char in[kSize * 2 + 1] = "0123456789ABCDEFGHIJKLMNOPQRSTUV";
    180   char out[kSize * 2];
    181   void* p;
    182   const void* q;
    183   size_t bytes;
    184   FifoBuffer buf(kSize);
    185   StreamInterface* stream = &buf;
    186 
    187   // Test assumptions about base state
    188   EXPECT_EQ(SS_OPEN, stream->GetState());
    189   EXPECT_EQ(SR_BLOCK, stream->Read(out, kSize, &bytes, NULL));
    190   EXPECT_TRUE(NULL != stream->GetReadData(&bytes));
    191   EXPECT_EQ((size_t)0, bytes);
    192   stream->ConsumeReadData(0);
    193   EXPECT_TRUE(NULL != stream->GetWriteBuffer(&bytes));
    194   EXPECT_EQ(kSize, bytes);
    195   stream->ConsumeWriteBuffer(0);
    196 
    197   // Try a full write
    198   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize, &bytes, NULL));
    199   EXPECT_EQ(kSize, bytes);
    200 
    201   // Try a write that should block
    202   EXPECT_EQ(SR_BLOCK, stream->Write(in, kSize, &bytes, NULL));
    203 
    204   // Try a full read
    205   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize, &bytes, NULL));
    206   EXPECT_EQ(kSize, bytes);
    207   EXPECT_EQ(0, memcmp(in, out, kSize));
    208 
    209   // Try a read that should block
    210   EXPECT_EQ(SR_BLOCK, stream->Read(out, kSize, &bytes, NULL));
    211 
    212   // Try a too-big write
    213   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize * 2, &bytes, NULL));
    214   EXPECT_EQ(bytes, kSize);
    215 
    216   // Try a too-big read
    217   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize * 2, &bytes, NULL));
    218   EXPECT_EQ(kSize, bytes);
    219   EXPECT_EQ(0, memcmp(in, out, kSize));
    220 
    221   // Try some small writes and reads
    222   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize / 2, &bytes, NULL));
    223   EXPECT_EQ(kSize / 2, bytes);
    224   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize / 2, &bytes, NULL));
    225   EXPECT_EQ(kSize / 2, bytes);
    226   EXPECT_EQ(0, memcmp(in, out, kSize / 2));
    227   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize / 2, &bytes, NULL));
    228   EXPECT_EQ(kSize / 2, bytes);
    229   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize / 2, &bytes, NULL));
    230   EXPECT_EQ(kSize / 2, bytes);
    231   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize / 2, &bytes, NULL));
    232   EXPECT_EQ(kSize / 2, bytes);
    233   EXPECT_EQ(0, memcmp(in, out, kSize / 2));
    234   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize / 2, &bytes, NULL));
    235   EXPECT_EQ(kSize / 2, bytes);
    236   EXPECT_EQ(0, memcmp(in, out, kSize / 2));
    237 
    238   // Try wraparound reads and writes in the following pattern
    239   // WWWWWWWWWWWW.... 0123456789AB....
    240   // RRRRRRRRXXXX.... ........89AB....
    241   // WWWW....XXXXWWWW 4567....89AB0123
    242   // XXXX....RRRRXXXX 4567........0123
    243   // XXXXWWWWWWWWXXXX 4567012345670123
    244   // RRRRXXXXXXXXRRRR ....01234567....
    245   // ....RRRRRRRR.... ................
    246   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize * 3 / 4, &bytes, NULL));
    247   EXPECT_EQ(kSize * 3 / 4, bytes);
    248   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize / 2, &bytes, NULL));
    249   EXPECT_EQ(kSize / 2, bytes);
    250   EXPECT_EQ(0, memcmp(in, out, kSize / 2));
    251   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize / 2, &bytes, NULL));
    252   EXPECT_EQ(kSize / 2, bytes);
    253   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize / 4, &bytes, NULL));
    254   EXPECT_EQ(kSize / 4 , bytes);
    255   EXPECT_EQ(0, memcmp(in + kSize / 2, out, kSize / 4));
    256   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize / 2, &bytes, NULL));
    257   EXPECT_EQ(kSize / 2, bytes);
    258   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize / 2, &bytes, NULL));
    259   EXPECT_EQ(kSize / 2 , bytes);
    260   EXPECT_EQ(0, memcmp(in, out, kSize / 2));
    261   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize / 2, &bytes, NULL));
    262   EXPECT_EQ(kSize / 2 , bytes);
    263   EXPECT_EQ(0, memcmp(in, out, kSize / 2));
    264 
    265   // Use GetWriteBuffer to reset the read_position for the next tests
    266   stream->GetWriteBuffer(&bytes);
    267   stream->ConsumeWriteBuffer(0);
    268 
    269   // Try using GetReadData to do a full read
    270   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize, &bytes, NULL));
    271   q = stream->GetReadData(&bytes);
    272   EXPECT_TRUE(NULL != q);
    273   EXPECT_EQ(kSize, bytes);
    274   EXPECT_EQ(0, memcmp(q, in, kSize));
    275   stream->ConsumeReadData(kSize);
    276   EXPECT_EQ(SR_BLOCK, stream->Read(out, kSize, &bytes, NULL));
    277 
    278   // Try using GetReadData to do some small reads
    279   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize, &bytes, NULL));
    280   q = stream->GetReadData(&bytes);
    281   EXPECT_TRUE(NULL != q);
    282   EXPECT_EQ(kSize, bytes);
    283   EXPECT_EQ(0, memcmp(q, in, kSize / 2));
    284   stream->ConsumeReadData(kSize / 2);
    285   q = stream->GetReadData(&bytes);
    286   EXPECT_TRUE(NULL != q);
    287   EXPECT_EQ(kSize / 2, bytes);
    288   EXPECT_EQ(0, memcmp(q, in + kSize / 2, kSize / 2));
    289   stream->ConsumeReadData(kSize / 2);
    290   EXPECT_EQ(SR_BLOCK, stream->Read(out, kSize, &bytes, NULL));
    291 
    292   // Try using GetReadData in a wraparound case
    293   // WWWWWWWWWWWWWWWW 0123456789ABCDEF
    294   // RRRRRRRRRRRRXXXX ............CDEF
    295   // WWWWWWWW....XXXX 01234567....CDEF
    296   // ............RRRR 01234567........
    297   // RRRRRRRR........ ................
    298   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize, &bytes, NULL));
    299   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize * 3 / 4, &bytes, NULL));
    300   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize / 2, &bytes, NULL));
    301   q = stream->GetReadData(&bytes);
    302   EXPECT_TRUE(NULL != q);
    303   EXPECT_EQ(kSize / 4, bytes);
    304   EXPECT_EQ(0, memcmp(q, in + kSize * 3 / 4, kSize / 4));
    305   stream->ConsumeReadData(kSize / 4);
    306   q = stream->GetReadData(&bytes);
    307   EXPECT_TRUE(NULL != q);
    308   EXPECT_EQ(kSize / 2, bytes);
    309   EXPECT_EQ(0, memcmp(q, in, kSize / 2));
    310   stream->ConsumeReadData(kSize / 2);
    311 
    312   // Use GetWriteBuffer to reset the read_position for the next tests
    313   stream->GetWriteBuffer(&bytes);
    314   stream->ConsumeWriteBuffer(0);
    315 
    316   // Try using GetWriteBuffer to do a full write
    317   p = stream->GetWriteBuffer(&bytes);
    318   EXPECT_TRUE(NULL != p);
    319   EXPECT_EQ(kSize, bytes);
    320   memcpy(p, in, kSize);
    321   stream->ConsumeWriteBuffer(kSize);
    322   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize, &bytes, NULL));
    323   EXPECT_EQ(kSize, bytes);
    324   EXPECT_EQ(0, memcmp(in, out, kSize));
    325 
    326   // Try using GetWriteBuffer to do some small writes
    327   p = stream->GetWriteBuffer(&bytes);
    328   EXPECT_TRUE(NULL != p);
    329   EXPECT_EQ(kSize, bytes);
    330   memcpy(p, in, kSize / 2);
    331   stream->ConsumeWriteBuffer(kSize / 2);
    332   p = stream->GetWriteBuffer(&bytes);
    333   EXPECT_TRUE(NULL != p);
    334   EXPECT_EQ(kSize / 2, bytes);
    335   memcpy(p, in + kSize / 2, kSize / 2);
    336   stream->ConsumeWriteBuffer(kSize / 2);
    337   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize, &bytes, NULL));
    338   EXPECT_EQ(kSize, bytes);
    339   EXPECT_EQ(0, memcmp(in, out, kSize));
    340 
    341   // Try using GetWriteBuffer in a wraparound case
    342   // WWWWWWWWWWWW.... 0123456789AB....
    343   // RRRRRRRRXXXX.... ........89AB....
    344   // ........XXXXWWWW ........89AB0123
    345   // WWWW....XXXXXXXX 4567....89AB0123
    346   // RRRR....RRRRRRRR ................
    347   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize * 3 / 4, &bytes, NULL));
    348   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize / 2, &bytes, NULL));
    349   p = stream->GetWriteBuffer(&bytes);
    350   EXPECT_TRUE(NULL != p);
    351   EXPECT_EQ(kSize / 4, bytes);
    352   memcpy(p, in, kSize / 4);
    353   stream->ConsumeWriteBuffer(kSize / 4);
    354   p = stream->GetWriteBuffer(&bytes);
    355   EXPECT_TRUE(NULL != p);
    356   EXPECT_EQ(kSize / 2, bytes);
    357   memcpy(p, in + kSize / 4, kSize / 4);
    358   stream->ConsumeWriteBuffer(kSize / 4);
    359   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize * 3 / 4, &bytes, NULL));
    360   EXPECT_EQ(kSize * 3 / 4, bytes);
    361   EXPECT_EQ(0, memcmp(in + kSize / 2, out, kSize / 4));
    362   EXPECT_EQ(0, memcmp(in, out + kSize / 4, kSize / 4));
    363 
    364   // Check that the stream is now empty
    365   EXPECT_EQ(SR_BLOCK, stream->Read(out, kSize, &bytes, NULL));
    366 
    367   // Try growing the buffer
    368   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize, &bytes, NULL));
    369   EXPECT_EQ(kSize, bytes);
    370   EXPECT_TRUE(buf.SetCapacity(kSize * 2));
    371   EXPECT_EQ(SR_SUCCESS, stream->Write(in + kSize, kSize, &bytes, NULL));
    372   EXPECT_EQ(kSize, bytes);
    373   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize * 2, &bytes, NULL));
    374   EXPECT_EQ(kSize * 2, bytes);
    375   EXPECT_EQ(0, memcmp(in, out, kSize * 2));
    376 
    377   // Try shrinking the buffer
    378   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize, &bytes, NULL));
    379   EXPECT_EQ(kSize, bytes);
    380   EXPECT_TRUE(buf.SetCapacity(kSize));
    381   EXPECT_EQ(SR_BLOCK, stream->Write(in, kSize, &bytes, NULL));
    382   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize, &bytes, NULL));
    383   EXPECT_EQ(kSize, bytes);
    384   EXPECT_EQ(0, memcmp(in, out, kSize));
    385 
    386   // Write to the stream, close it, read the remaining bytes
    387   EXPECT_EQ(SR_SUCCESS, stream->Write(in, kSize / 2, &bytes, NULL));
    388   stream->Close();
    389   EXPECT_EQ(SS_CLOSED, stream->GetState());
    390   EXPECT_EQ(SR_EOS, stream->Write(in, kSize / 2, &bytes, NULL));
    391   EXPECT_EQ(SR_SUCCESS, stream->Read(out, kSize / 2, &bytes, NULL));
    392   EXPECT_EQ(0, memcmp(in, out, kSize / 2));
    393   EXPECT_EQ(SR_EOS, stream->Read(out, kSize / 2, &bytes, NULL));
    394 }
    395 
    396 TEST(FifoBufferTest, FullBufferCheck) {
    397   FifoBuffer buff(10);
    398   buff.ConsumeWriteBuffer(10);
    399 
    400   size_t free;
    401   EXPECT_TRUE(buff.GetWriteBuffer(&free) != NULL);
    402   EXPECT_EQ(0U, free);
    403 }
    404 
    405 TEST(FifoBufferTest, WriteOffsetAndReadOffset) {
    406   const size_t kSize = 16;
    407   const char in[kSize * 2 + 1] = "0123456789ABCDEFGHIJKLMNOPQRSTUV";
    408   char out[kSize * 2];
    409   FifoBuffer buf(kSize);
    410 
    411   // Write 14 bytes.
    412   EXPECT_EQ(SR_SUCCESS, buf.Write(in, 14, NULL, NULL));
    413 
    414   // Make sure data is in |buf|.
    415   size_t buffered;
    416   EXPECT_TRUE(buf.GetBuffered(&buffered));
    417   EXPECT_EQ(14u, buffered);
    418 
    419   // Read 10 bytes.
    420   buf.ConsumeReadData(10);
    421 
    422   // There should be now 12 bytes of available space.
    423   size_t remaining;
    424   EXPECT_TRUE(buf.GetWriteRemaining(&remaining));
    425   EXPECT_EQ(12u, remaining);
    426 
    427   // Write at offset 12, this should fail.
    428   EXPECT_EQ(SR_BLOCK, buf.WriteOffset(in, 10, 12, NULL));
    429 
    430   // Write 8 bytes at offset 4, this wraps around the buffer.
    431   EXPECT_EQ(SR_SUCCESS, buf.WriteOffset(in, 8, 4, NULL));
    432 
    433   // Number of available space remains the same until we call
    434   // ConsumeWriteBuffer().
    435   EXPECT_TRUE(buf.GetWriteRemaining(&remaining));
    436   EXPECT_EQ(12u, remaining);
    437   buf.ConsumeWriteBuffer(12);
    438 
    439   // There's 4 bytes bypassed and 4 bytes no read so skip them and verify the
    440   // 8 bytes written.
    441   size_t read;
    442   EXPECT_EQ(SR_SUCCESS, buf.ReadOffset(out, 8, 8, &read));
    443   EXPECT_EQ(8u, read);
    444   EXPECT_EQ(0, memcmp(out, in, 8));
    445 
    446   // There should still be 16 bytes available for reading.
    447   EXPECT_TRUE(buf.GetBuffered(&buffered));
    448   EXPECT_EQ(16u, buffered);
    449 
    450   // Read at offset 16, this should fail since we don't have that much data.
    451   EXPECT_EQ(SR_BLOCK, buf.ReadOffset(out, 10, 16, NULL));
    452 }
    453 
    454 TEST(AsyncWriteTest, TestWrite) {
    455   FifoBuffer* buf = new FifoBuffer(100);
    456   AsyncWriteStream stream(buf, Thread::Current());
    457   EXPECT_EQ(SS_OPEN, stream.GetState());
    458 
    459   // Write "abc".  Will go to the logging thread, which is the current
    460   // thread.
    461   stream.Write("abc", 3, NULL, NULL);
    462   char bytes[100];
    463   size_t count;
    464   // Messages on the thread's queue haven't been processed, so "abc"
    465   // hasn't been written yet.
    466   EXPECT_NE(SR_SUCCESS, buf->ReadOffset(&bytes, 3, 0, &count));
    467   // Now we process the messages on the thread's queue, so "abc" has
    468   // been written.
    469   EXPECT_TRUE_WAIT(SR_SUCCESS == buf->ReadOffset(&bytes, 3, 0, &count), 10);
    470   EXPECT_EQ(3u, count);
    471   EXPECT_EQ(0, memcmp(bytes, "abc", 3));
    472 
    473   // Write "def".  Will go to the logging thread, which is the current
    474   // thread.
    475   stream.Write("d", 1, &count, NULL);
    476   stream.Write("e", 1, &count, NULL);
    477   stream.Write("f", 1, &count, NULL);
    478   EXPECT_EQ(1u, count);
    479   // Messages on the thread's queue haven't been processed, so "def"
    480   // hasn't been written yet.
    481   EXPECT_NE(SR_SUCCESS, buf->ReadOffset(&bytes, 3, 3, &count));
    482   // Flush() causes the message to be processed, so "def" has now been
    483   // written.
    484   stream.Flush();
    485   EXPECT_EQ(SR_SUCCESS, buf->ReadOffset(&bytes, 3, 3, &count));
    486   EXPECT_EQ(3u, count);
    487   EXPECT_EQ(0, memcmp(bytes, "def", 3));
    488 
    489   // Write "xyz".  Will go to the logging thread, which is the current
    490   // thread.
    491   stream.Write("xyz", 3, &count, NULL);
    492   EXPECT_EQ(3u, count);
    493   // Messages on the thread's queue haven't been processed, so "xyz"
    494   // hasn't been written yet.
    495   EXPECT_NE(SR_SUCCESS, buf->ReadOffset(&bytes, 3, 6, &count));
    496   // Close() causes the message to be processed, so "xyz" has now been
    497   // written.
    498   stream.Close();
    499   EXPECT_EQ(SR_SUCCESS, buf->ReadOffset(&bytes, 3, 6, &count));
    500   EXPECT_EQ(3u, count);
    501   EXPECT_EQ(0, memcmp(bytes, "xyz", 3));
    502   EXPECT_EQ(SS_CLOSED, stream.GetState());
    503 
    504   // Is't closed, so the writes should fail.
    505   EXPECT_EQ(SR_ERROR, stream.Write("000", 3, NULL, NULL));
    506 
    507 }
    508 
    509 }  // namespace talk_base
    510