Implement a MOJO_READ_DATA_FLAG_PEEK flag for data pipes.
MOJO_READ_DATA_FLAG_PEEK allows the user to read data from a pipe
without removing it. The data will be available for the next read.
R=viettrungluu@chromium.org
Review URL: https://codereview.chromium.org/703573002
diff --git a/mojo/edk/system/core_unittest.cc b/mojo/edk/system/core_unittest.cc
index 9adde19..e6607df 100644
--- a/mojo/edk/system/core_unittest.cc
+++ b/mojo/edk/system/core_unittest.cc
@@ -1084,6 +1084,19 @@
EXPECT_EQ(MOJO_HANDLE_SIGNAL_READABLE, hss.satisfied_signals);
EXPECT_EQ(MOJO_HANDLE_SIGNAL_READABLE, hss.satisfiable_signals);
+ // Peek one character.
+ elements[0] = -1;
+ elements[1] = -1;
+ num_bytes = 1u;
+ EXPECT_EQ(MOJO_RESULT_OK,
+ core()->ReadData(
+ ch,
+ UserPointer<void>(elements),
+ MakeUserPointer(&num_bytes),
+ MOJO_READ_DATA_FLAG_NONE | MOJO_READ_DATA_FLAG_PEEK));
+ EXPECT_EQ('A', elements[0]);
+ EXPECT_EQ(-1, elements[1]);
+
// Read one character.
elements[0] = -1;
elements[1] = -1;
@@ -1131,6 +1144,16 @@
MOJO_READ_DATA_FLAG_QUERY));
EXPECT_EQ(4u, num_bytes);
+ // Try to query with peek. Should fail.
+ num_bytes = 0;
+ EXPECT_EQ(MOJO_RESULT_INVALID_ARGUMENT,
+ core()->ReadData(
+ ch,
+ NullUserPointer(),
+ MakeUserPointer(&num_bytes),
+ MOJO_READ_DATA_FLAG_QUERY | MOJO_READ_DATA_FLAG_PEEK));
+ EXPECT_EQ(0u, num_bytes);
+
// Try to discard ten characters, in all-or-none mode. Should fail.
num_bytes = 10;
EXPECT_EQ(MOJO_RESULT_OUT_OF_RANGE,
@@ -1140,6 +1163,15 @@
MakeUserPointer(&num_bytes),
MOJO_READ_DATA_FLAG_DISCARD | MOJO_READ_DATA_FLAG_ALL_OR_NONE));
+ // Try to discard two characters, in peek mode. Should fail.
+ num_bytes = 2;
+ EXPECT_EQ(MOJO_RESULT_INVALID_ARGUMENT,
+ core()->ReadData(
+ ch,
+ NullUserPointer(),
+ MakeUserPointer(&num_bytes),
+ MOJO_READ_DATA_FLAG_DISCARD | MOJO_READ_DATA_FLAG_PEEK));
+
// Discard two characters.
num_bytes = 2;
EXPECT_EQ(MOJO_RESULT_OK,
@@ -1149,9 +1181,17 @@
MakeUserPointer(&num_bytes),
MOJO_READ_DATA_FLAG_DISCARD | MOJO_READ_DATA_FLAG_ALL_OR_NONE));
- // Read the remaining two characters, in two-phase mode (all-or-none).
+ // Try a two-phase read of the remaining two bytes with peek. Should fail.
const void* read_ptr = nullptr;
num_bytes = 2;
+ ASSERT_EQ(MOJO_RESULT_INVALID_ARGUMENT,
+ core()->BeginReadData(ch,
+ MakeUserPointer(&read_ptr),
+ MakeUserPointer(&num_bytes),
+ MOJO_READ_DATA_FLAG_PEEK));
+
+ // Read the remaining two characters, in two-phase mode (all-or-none).
+ num_bytes = 2;
ASSERT_EQ(MOJO_RESULT_OK,
core()->BeginReadData(ch,
MakeUserPointer(&read_ptr),
diff --git a/mojo/edk/system/data_pipe.cc b/mojo/edk/system/data_pipe.cc
index e9c4903..e9525bc 100644
--- a/mojo/edk/system/data_pipe.cc
+++ b/mojo/edk/system/data_pipe.cc
@@ -260,7 +260,8 @@
MojoResult DataPipe::ConsumerReadData(UserPointer<void> elements,
UserPointer<uint32_t> num_bytes,
- bool all_or_none) {
+ bool all_or_none,
+ bool peek) {
base::AutoLock locker(lock_);
DCHECK(has_local_consumer_no_lock());
@@ -279,7 +280,7 @@
HandleSignalsState old_producer_state =
ProducerGetHandleSignalsStateImplNoLock();
MojoResult rv = ConsumerReadDataImplNoLock(
- elements, num_bytes, max_num_bytes_to_read, min_num_bytes_to_read);
+ elements, num_bytes, max_num_bytes_to_read, min_num_bytes_to_read, peek);
HandleSignalsState new_producer_state =
ProducerGetHandleSignalsStateImplNoLock();
if (!new_producer_state.equals(old_producer_state))
diff --git a/mojo/edk/system/data_pipe.h b/mojo/edk/system/data_pipe.h
index 64b18e2..d4afdda 100644
--- a/mojo/edk/system/data_pipe.h
+++ b/mojo/edk/system/data_pipe.h
@@ -73,7 +73,8 @@
// a multiple of |element_num_bytes_|.
MojoResult ConsumerReadData(UserPointer<void> elements,
UserPointer<uint32_t> num_bytes,
- bool all_or_none);
+ bool all_or_none,
+ bool peek);
MojoResult ConsumerDiscardData(UserPointer<uint32_t> num_bytes,
bool all_or_none);
MojoResult ConsumerQueryData(UserPointer<uint32_t> num_bytes);
@@ -120,7 +121,8 @@
UserPointer<void> elements,
UserPointer<uint32_t> num_bytes,
uint32_t max_num_bytes_to_read,
- uint32_t min_num_bytes_to_read) = 0;
+ uint32_t min_num_bytes_to_read,
+ bool peek) = 0;
virtual MojoResult ConsumerDiscardDataImplNoLock(
UserPointer<uint32_t> num_bytes,
uint32_t max_num_bytes_to_discard,
diff --git a/mojo/edk/system/data_pipe_consumer_dispatcher.cc b/mojo/edk/system/data_pipe_consumer_dispatcher.cc
index 2b3f514..f2d4496 100644
--- a/mojo/edk/system/data_pipe_consumer_dispatcher.cc
+++ b/mojo/edk/system/data_pipe_consumer_dispatcher.cc
@@ -58,7 +58,8 @@
if ((flags & MOJO_READ_DATA_FLAG_DISCARD)) {
// These flags are mutally exclusive.
- if ((flags & MOJO_READ_DATA_FLAG_QUERY))
+ if ((flags & MOJO_READ_DATA_FLAG_QUERY) ||
+ (flags & MOJO_READ_DATA_FLAG_PEEK))
return MOJO_RESULT_INVALID_ARGUMENT;
DVLOG_IF(2, !elements.IsNull())
<< "Discard mode: ignoring non-null |elements|";
@@ -67,6 +68,8 @@
}
if ((flags & MOJO_READ_DATA_FLAG_QUERY)) {
+ if ((flags & MOJO_READ_DATA_FLAG_PEEK))
+ return MOJO_RESULT_INVALID_ARGUMENT;
DCHECK(!(flags & MOJO_READ_DATA_FLAG_DISCARD)); // Handled above.
DVLOG_IF(2, !elements.IsNull())
<< "Query mode: ignoring non-null |elements|";
@@ -74,7 +77,10 @@
}
return data_pipe_->ConsumerReadData(
- elements, num_bytes, (flags & MOJO_READ_DATA_FLAG_ALL_OR_NONE));
+ elements,
+ num_bytes,
+ (flags & MOJO_READ_DATA_FLAG_ALL_OR_NONE),
+ (flags & MOJO_READ_DATA_FLAG_PEEK));
}
MojoResult DataPipeConsumerDispatcher::BeginReadDataImplNoLock(
@@ -85,7 +91,8 @@
// These flags may not be used in two-phase mode.
if ((flags & MOJO_READ_DATA_FLAG_DISCARD) ||
- (flags & MOJO_READ_DATA_FLAG_QUERY))
+ (flags & MOJO_READ_DATA_FLAG_QUERY) ||
+ (flags & MOJO_READ_DATA_FLAG_PEEK))
return MOJO_RESULT_INVALID_ARGUMENT;
return data_pipe_->ConsumerBeginReadData(
diff --git a/mojo/edk/system/local_data_pipe.cc b/mojo/edk/system/local_data_pipe.cc
index 8ee696c..fdfaf28 100644
--- a/mojo/edk/system/local_data_pipe.cc
+++ b/mojo/edk/system/local_data_pipe.cc
@@ -177,7 +177,8 @@
UserPointer<void> elements,
UserPointer<uint32_t> num_bytes,
uint32_t max_num_bytes_to_read,
- uint32_t min_num_bytes_to_read) {
+ uint32_t min_num_bytes_to_read,
+ bool peek) {
DCHECK_EQ(max_num_bytes_to_read % element_num_bytes(), 0u);
DCHECK_EQ(min_num_bytes_to_read % element_num_bytes(), 0u);
DCHECK_GT(max_num_bytes_to_read, 0u);
@@ -207,7 +208,8 @@
.PutArray(buffer_.get(), num_bytes_to_read - num_bytes_to_read_first);
}
- MarkDataAsConsumedNoLock(num_bytes_to_read);
+ if (!peek)
+ MarkDataAsConsumedNoLock(num_bytes_to_read);
num_bytes.Put(static_cast<uint32_t>(num_bytes_to_read));
return MOJO_RESULT_OK;
}
diff --git a/mojo/edk/system/local_data_pipe.h b/mojo/edk/system/local_data_pipe.h
index 8a46c52..c98cb7e 100644
--- a/mojo/edk/system/local_data_pipe.h
+++ b/mojo/edk/system/local_data_pipe.h
@@ -48,7 +48,8 @@
UserPointer<void> elements,
UserPointer<uint32_t> num_bytes,
uint32_t max_num_bytes_to_read,
- uint32_t min_num_bytes_to_read) override;
+ uint32_t min_num_bytes_to_read,
+ bool peek) override;
MojoResult ConsumerDiscardDataImplNoLock(
UserPointer<uint32_t> num_bytes,
uint32_t max_num_bytes_to_discard,
diff --git a/mojo/edk/system/local_data_pipe_unittest.cc b/mojo/edk/system/local_data_pipe_unittest.cc
index 979b4d2..e8bc716 100644
--- a/mojo/edk/system/local_data_pipe_unittest.cc
+++ b/mojo/edk/system/local_data_pipe_unittest.cc
@@ -118,8 +118,10 @@
num_bytes = static_cast<uint32_t>(arraysize(elements) * sizeof(elements[0]));
EXPECT_EQ(
MOJO_RESULT_SHOULD_WAIT,
- dp->ConsumerReadData(
- UserPointer<void>(elements), MakeUserPointer(&num_bytes), false));
+ dp->ConsumerReadData(UserPointer<void>(elements),
+ MakeUserPointer(&num_bytes),
+ false,
+ false));
// Query; nothing there yet.
num_bytes = 0;
@@ -135,8 +137,10 @@
num_bytes = sizeof(elements[0]) + 1;
EXPECT_EQ(
MOJO_RESULT_INVALID_ARGUMENT,
- dp->ConsumerReadData(
- UserPointer<void>(elements), MakeUserPointer(&num_bytes), false));
+ dp->ConsumerReadData(UserPointer<void>(elements),
+ MakeUserPointer(&num_bytes),
+ false,
+ false));
// Write two elements.
elements[0] = 123;
@@ -160,8 +164,10 @@
num_bytes = static_cast<uint32_t>(1u * sizeof(elements[0]));
EXPECT_EQ(
MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(elements), MakeUserPointer(&num_bytes), false));
+ dp->ConsumerReadData(UserPointer<void>(elements),
+ MakeUserPointer(&num_bytes),
+ false,
+ false));
EXPECT_EQ(1u * sizeof(elements[0]), num_bytes);
EXPECT_EQ(123, elements[0]);
EXPECT_EQ(-1, elements[1]);
@@ -171,14 +177,35 @@
EXPECT_EQ(MOJO_RESULT_OK, dp->ConsumerQueryData(MakeUserPointer(&num_bytes)));
EXPECT_EQ(1 * sizeof(elements[0]), num_bytes);
+ // Peek one element.
+ elements[0] = -1;
+ elements[1] = -1;
+ num_bytes = static_cast<uint32_t>(1u * sizeof(elements[0]));
+ EXPECT_EQ(
+ MOJO_RESULT_OK,
+ dp->ConsumerReadData(UserPointer<void>(elements),
+ MakeUserPointer(&num_bytes),
+ false,
+ true));
+ EXPECT_EQ(1u * sizeof(elements[0]), num_bytes);
+ EXPECT_EQ(456, elements[0]);
+ EXPECT_EQ(-1, elements[1]);
+
+ // Query. Still has 1 element remaining.
+ num_bytes = 0;
+ EXPECT_EQ(MOJO_RESULT_OK, dp->ConsumerQueryData(MakeUserPointer(&num_bytes)));
+ EXPECT_EQ(1 * sizeof(elements[0]), num_bytes);
+
// Try to read two elements, with "all or none".
elements[0] = -1;
elements[1] = -1;
num_bytes = static_cast<uint32_t>(2u * sizeof(elements[0]));
EXPECT_EQ(
MOJO_RESULT_OUT_OF_RANGE,
- dp->ConsumerReadData(
- UserPointer<void>(elements), MakeUserPointer(&num_bytes), true));
+ dp->ConsumerReadData(UserPointer<void>(elements),
+ MakeUserPointer(&num_bytes),
+ true,
+ false));
EXPECT_EQ(-1, elements[0]);
EXPECT_EQ(-1, elements[1]);
@@ -188,8 +215,10 @@
num_bytes = static_cast<uint32_t>(2u * sizeof(elements[0]));
EXPECT_EQ(
MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(elements), MakeUserPointer(&num_bytes), false));
+ dp->ConsumerReadData(UserPointer<void>(elements),
+ MakeUserPointer(&num_bytes),
+ false,
+ false));
EXPECT_EQ(456, elements[0]);
EXPECT_EQ(-1, elements[1]);
@@ -262,6 +291,32 @@
EXPECT_EQ(0u, hss.satisfied_signals);
EXPECT_EQ(MOJO_HANDLE_SIGNAL_WRITABLE, hss.satisfiable_signals);
+ // Peek one element.
+ elements[0] = -1;
+ elements[1] = -1;
+ num_bytes = static_cast<uint32_t>(1u * sizeof(elements[0]));
+ EXPECT_EQ(
+ MOJO_RESULT_OK,
+ dp->ConsumerReadData(UserPointer<void>(elements),
+ MakeUserPointer(&num_bytes),
+ true,
+ true));
+ EXPECT_EQ(static_cast<uint32_t>(1u * sizeof(elements[0])), num_bytes);
+ EXPECT_EQ(123, elements[0]);
+ EXPECT_EQ(-1, elements[1]);
+
+ // Add a waiter.
+ waiter.Init();
+ ASSERT_EQ(
+ MOJO_RESULT_OK,
+ dp->ProducerAddWaiter(&waiter, MOJO_HANDLE_SIGNAL_WRITABLE, 56, nullptr));
+ // And it still shouldn't be writable yet.
+ EXPECT_EQ(MOJO_RESULT_DEADLINE_EXCEEDED, waiter.Wait(0, nullptr));
+ hss = HandleSignalsState();
+ dp->ProducerRemoveWaiter(&waiter, &hss);
+ EXPECT_EQ(0u, hss.satisfied_signals);
+ EXPECT_EQ(MOJO_HANDLE_SIGNAL_WRITABLE, hss.satisfiable_signals);
+
// Do it again.
waiter.Init();
ASSERT_EQ(
@@ -274,8 +329,10 @@
num_bytes = static_cast<uint32_t>(1u * sizeof(elements[0]));
EXPECT_EQ(
MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(elements), MakeUserPointer(&num_bytes), true));
+ dp->ConsumerReadData(UserPointer<void>(elements),
+ MakeUserPointer(&num_bytes),
+ true,
+ false));
EXPECT_EQ(static_cast<uint32_t>(1u * sizeof(elements[0])), num_bytes);
EXPECT_EQ(123, elements[0]);
EXPECT_EQ(-1, elements[1]);
@@ -432,14 +489,39 @@
EXPECT_EQ(MOJO_HANDLE_SIGNAL_READABLE, hss.satisfied_signals);
EXPECT_EQ(MOJO_HANDLE_SIGNAL_READABLE, hss.satisfiable_signals);
+ // Peek one element.
+ elements[0] = -1;
+ elements[1] = -1;
+ num_bytes = static_cast<uint32_t>(1u * sizeof(elements[0]));
+ EXPECT_EQ(
+ MOJO_RESULT_OK,
+ dp->ConsumerReadData(UserPointer<void>(elements),
+ MakeUserPointer(&num_bytes),
+ true,
+ true));
+ EXPECT_EQ(static_cast<uint32_t>(1u * sizeof(elements[0])), num_bytes);
+ EXPECT_EQ(456, elements[0]);
+ EXPECT_EQ(-1, elements[1]);
+
+ // Should still be readable.
+ waiter.Init();
+ hss = HandleSignalsState();
+ EXPECT_EQ(
+ MOJO_RESULT_ALREADY_EXISTS,
+ dp->ConsumerAddWaiter(&waiter, MOJO_HANDLE_SIGNAL_READABLE, 78, &hss));
+ EXPECT_EQ(MOJO_HANDLE_SIGNAL_READABLE, hss.satisfied_signals);
+ EXPECT_EQ(MOJO_HANDLE_SIGNAL_READABLE, hss.satisfiable_signals);
+
// Read one element.
elements[0] = -1;
elements[1] = -1;
num_bytes = static_cast<uint32_t>(1u * sizeof(elements[0]));
EXPECT_EQ(
MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(elements), MakeUserPointer(&num_bytes), true));
+ dp->ConsumerReadData(UserPointer<void>(elements),
+ MakeUserPointer(&num_bytes),
+ true,
+ false));
EXPECT_EQ(static_cast<uint32_t>(1u * sizeof(elements[0])), num_bytes);
EXPECT_EQ(456, elements[0]);
EXPECT_EQ(-1, elements[1]);
@@ -485,8 +567,10 @@
num_bytes = static_cast<uint32_t>(1u * sizeof(elements[0]));
EXPECT_EQ(
MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(elements), MakeUserPointer(&num_bytes), true));
+ dp->ConsumerReadData(UserPointer<void>(elements),
+ MakeUserPointer(&num_bytes),
+ true,
+ false));
EXPECT_EQ(static_cast<uint32_t>(1u * sizeof(elements[0])), num_bytes);
EXPECT_EQ(789, elements[0]);
EXPECT_EQ(-1, elements[1]);
@@ -843,8 +927,10 @@
element = 0;
EXPECT_EQ(
MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(&element), MakeUserPointer(&num_bytes), false));
+ dp->ConsumerReadData(UserPointer<void>(&element),
+ MakeUserPointer(&num_bytes),
+ false,
+ false));
EXPECT_EQ(static_cast<uint32_t>(sizeof(int32_t)), num_bytes);
EXPECT_EQ(456, element);
@@ -908,8 +994,10 @@
num_bytes = 5u * sizeof(int32_t);
memset(buffer, 0xab, sizeof(buffer));
EXPECT_EQ(MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(buffer), MakeUserPointer(&num_bytes), false));
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ false,
+ false));
EXPECT_EQ(5u * sizeof(int32_t), num_bytes);
int32_t expected_buffer[100];
memset(expected_buffer, 0xab, sizeof(expected_buffer));
@@ -933,8 +1021,10 @@
num_bytes = 5u * sizeof(int32_t);
memset(buffer, 0xab, sizeof(buffer));
EXPECT_EQ(MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(buffer), MakeUserPointer(&num_bytes), false));
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ false,
+ false));
EXPECT_EQ(5u * sizeof(int32_t), num_bytes);
memset(expected_buffer, 0xab, sizeof(expected_buffer));
expected_buffer[0] = 8;
@@ -972,8 +1062,10 @@
num_bytes = sizeof(buffer);
memset(buffer, 0xab, sizeof(buffer));
EXPECT_EQ(MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(buffer), MakeUserPointer(&num_bytes), false));
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ false,
+ false));
EXPECT_EQ(10u * sizeof(int32_t), num_bytes);
memset(expected_buffer, 0xab, sizeof(expected_buffer));
expected_buffer[0] = 104;
@@ -1062,8 +1154,10 @@
num_bytes = sizeof(buffer);
memset(buffer, 0xab, sizeof(buffer));
EXPECT_EQ(MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(buffer), MakeUserPointer(&num_bytes), false));
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ false,
+ false));
EXPECT_EQ(8u * sizeof(int32_t), num_bytes);
memset(expected_buffer, 0xab, sizeof(expected_buffer));
expected_buffer[0] = 500;
@@ -1134,8 +1228,10 @@
num_bytes = 11u * sizeof(int32_t);
memset(buffer, 0xab, sizeof(buffer));
EXPECT_EQ(MOJO_RESULT_OUT_OF_RANGE,
- dp->ConsumerReadData(
- UserPointer<void>(buffer), MakeUserPointer(&num_bytes), true));
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ true,
+ false));
int32_t expected_buffer[100];
memset(expected_buffer, 0xab, sizeof(expected_buffer));
EXPECT_EQ(0, memcmp(buffer, expected_buffer, sizeof(buffer)));
@@ -1172,8 +1268,10 @@
num_bytes = 5u * sizeof(int32_t);
memset(buffer, 0xab, sizeof(buffer));
EXPECT_EQ(MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(buffer), MakeUserPointer(&num_bytes), true));
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ true,
+ false));
EXPECT_EQ(5u * sizeof(int32_t), num_bytes);
memset(expected_buffer, 0xab, sizeof(expected_buffer));
Seq(100, 5, expected_buffer);
@@ -1183,8 +1281,10 @@
num_bytes = 6u * sizeof(int32_t);
memset(buffer, 0xab, sizeof(buffer));
EXPECT_EQ(MOJO_RESULT_OUT_OF_RANGE,
- dp->ConsumerReadData(
- UserPointer<void>(buffer), MakeUserPointer(&num_bytes), true));
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ true,
+ false));
memset(expected_buffer, 0xab, sizeof(expected_buffer));
EXPECT_EQ(0, memcmp(buffer, expected_buffer, sizeof(buffer)));
@@ -1211,8 +1311,10 @@
num_bytes = 4u * sizeof(int32_t);
memset(buffer, 0xab, sizeof(buffer));
EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION,
- dp->ConsumerReadData(
- UserPointer<void>(buffer), MakeUserPointer(&num_bytes), true));
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ true,
+ false));
memset(expected_buffer, 0xab, sizeof(expected_buffer));
EXPECT_EQ(0, memcmp(buffer, expected_buffer, sizeof(buffer)));
@@ -1225,8 +1327,10 @@
num_bytes = 2u * sizeof(int32_t);
memset(buffer, 0xab, sizeof(buffer));
EXPECT_EQ(MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(buffer), MakeUserPointer(&num_bytes), true));
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ true,
+ false));
EXPECT_EQ(2u * sizeof(int32_t), num_bytes);
memset(expected_buffer, 0xab, sizeof(expected_buffer));
Seq(400, 2, expected_buffer);
@@ -1291,8 +1395,10 @@
num_bytes = 1u * sizeof(int32_t);
memset(buffer, 0xab, sizeof(buffer));
EXPECT_EQ(MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(buffer), MakeUserPointer(&num_bytes), true));
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ true,
+ false));
EXPECT_EQ(1u * sizeof(int32_t), num_bytes);
int32_t expected_buffer[100];
memset(expected_buffer, 0xab, sizeof(expected_buffer));
@@ -1303,8 +1409,10 @@
num_bytes = 10u * sizeof(int32_t);
memset(buffer, 0xab, sizeof(buffer));
EXPECT_EQ(MOJO_RESULT_OUT_OF_RANGE,
- dp->ConsumerReadData(
- UserPointer<void>(buffer), MakeUserPointer(&num_bytes), true));
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ true,
+ false));
memset(expected_buffer, 0xab, sizeof(expected_buffer));
EXPECT_EQ(0, memcmp(buffer, expected_buffer, sizeof(buffer)));
@@ -1336,8 +1444,10 @@
num_bytes = 10u * sizeof(int32_t);
memset(buffer, 0xab, sizeof(buffer));
EXPECT_EQ(MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(buffer), MakeUserPointer(&num_bytes), true));
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ true,
+ false));
memset(expected_buffer, 0xab, sizeof(expected_buffer));
EXPECT_EQ(10u * sizeof(int32_t), num_bytes);
Seq(300, 10, expected_buffer);
@@ -1525,8 +1635,10 @@
num_bytes = 10u;
EXPECT_EQ(
MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(read_buffer), MakeUserPointer(&num_bytes), false));
+ dp->ConsumerReadData(UserPointer<void>(read_buffer),
+ MakeUserPointer(&num_bytes),
+ false,
+ false));
EXPECT_EQ(10u, num_bytes);
EXPECT_EQ(0, memcmp(read_buffer, &test_data[0], 10u));
@@ -1572,8 +1684,10 @@
memset(read_buffer, 0, num_bytes);
EXPECT_EQ(
MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(read_buffer), MakeUserPointer(&num_bytes), false));
+ dp->ConsumerReadData(UserPointer<void>(read_buffer),
+ MakeUserPointer(&num_bytes),
+ false,
+ false));
EXPECT_EQ(100u, num_bytes);
EXPECT_EQ(0, memcmp(read_buffer, &test_data[10], 100u));
@@ -1753,13 +1867,27 @@
// Close the producer.
dp->ProducerClose();
- // Read that data.
+ // Peek that data.
char buffer[1000];
num_bytes = static_cast<uint32_t>(sizeof(buffer));
EXPECT_EQ(
MOJO_RESULT_OK,
- dp->ConsumerReadData(
- UserPointer<void>(buffer), MakeUserPointer(&num_bytes), false));
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ false,
+ true));
+ EXPECT_EQ(kTestDataSize, num_bytes);
+ EXPECT_EQ(0, memcmp(buffer, kTestData, kTestDataSize));
+
+ // Read that data.
+ memset(buffer, 0, 1000);
+ num_bytes = static_cast<uint32_t>(sizeof(buffer));
+ EXPECT_EQ(
+ MOJO_RESULT_OK,
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ false,
+ false));
EXPECT_EQ(kTestDataSize, num_bytes);
EXPECT_EQ(0, memcmp(buffer, kTestData, kTestDataSize));
@@ -1767,8 +1895,10 @@
num_bytes = static_cast<uint32_t>(sizeof(buffer));
EXPECT_EQ(
MOJO_RESULT_FAILED_PRECONDITION,
- dp->ConsumerReadData(
- UserPointer<void>(buffer), MakeUserPointer(&num_bytes), false));
+ dp->ConsumerReadData(UserPointer<void>(buffer),
+ MakeUserPointer(&num_bytes),
+ false,
+ false));
// A two-phase read should also fail.
const void* read_buffer_ptr = nullptr;
diff --git a/mojo/public/c/system/data_pipe.h b/mojo/public/c/system/data_pipe.h
index a7498e4..089ead3 100644
--- a/mojo/public/c/system/data_pipe.h
+++ b/mojo/public/c/system/data_pipe.h
@@ -83,6 +83,9 @@
// read. For use with |MojoReadData()| only. Mutually exclusive with
// |MOJO_READ_DATA_FLAG_DISCARD| and |MOJO_READ_DATA_FLAG_ALL_OR_NONE| is
// ignored if this flag is set.
+// |MOJO_READ_DATA_FLAG_PEEK| - Read elements without removing them. For use
+// with |MojoReadData()| only. Mutually exclusive with
+// |MOJO_READ_DATA_FLAG_DISCARD| and |MOJO_READ_DATA_FLAG_QUERY|.
typedef uint32_t MojoReadDataFlags;
@@ -91,11 +94,13 @@
const MojoReadDataFlags MOJO_READ_DATA_FLAG_ALL_OR_NONE = 1 << 0;
const MojoReadDataFlags MOJO_READ_DATA_FLAG_DISCARD = 1 << 1;
const MojoReadDataFlags MOJO_READ_DATA_FLAG_QUERY = 1 << 2;
+const MojoReadDataFlags MOJO_READ_DATA_FLAG_PEEK = 1 << 3;
#else
#define MOJO_READ_DATA_FLAG_NONE ((MojoReadDataFlags)0)
#define MOJO_READ_DATA_FLAG_ALL_OR_NONE ((MojoReadDataFlags)1 << 0)
#define MOJO_READ_DATA_FLAG_DISCARD ((MojoReadDataFlags)1 << 1)
#define MOJO_READ_DATA_FLAG_QUERY ((MojoReadDataFlags)1 << 2)
+#define MOJO_READ_DATA_FLAG_PEEK ((MojoReadDataFlags)1 << 3)
#endif
#ifdef __cplusplus
@@ -254,7 +259,9 @@
// must be a multiple of the data pipe's element size) bytes of data to
// |elements| and set |*num_bytes| to the amount actually read. If flags has
// |MOJO_READ_DATA_FLAG_ALL_OR_NONE| set, it will either read exactly
-// |*num_bytes| bytes of data or none.
+// |*num_bytes| bytes of data or none. Additionally, if flags has
+// |MOJO_READ_DATA_FLAG_PEEK| set, the data read will remain in the pipe and be
+// available to future reads.
//
// If flags has |MOJO_READ_DATA_FLAG_DISCARD| set, it discards up to
// |*num_bytes| (which again be a multiple of the element size) bytes of data,
@@ -300,7 +307,8 @@
// |*buffer_num_bytes| will be at least as large as its input value, which must
// also be a multiple of the element size (if |MOJO_READ_DATA_FLAG_ALL_OR_NONE|
// is not set, the input value of |*buffer_num_bytes| is ignored). |flags| must
-// not have |MOJO_READ_DATA_FLAG_DISCARD| or |MOJO_READ_DATA_FLAG_QUERY| set.
+// not have |MOJO_READ_DATA_FLAG_DISCARD|, |MOJO_READ_DATA_FLAG_QUERY|, or
+// |MOJO_READ_DATA_FLAG_PEEK| set.
//
// During a two-phase read, |data_pipe_consumer_handle| is *not* readable.
// E.g., if another thread tries to read from it, it will get
