class InStream

class InStream

Defined at line 32 of file ../../src/media/codec/examples/use_media_decoder/test/../in_stream.h

Abstract base class which permits reading from a stream of input data.

Sub-classes:

* InStreamFile can stream in from a file.

* InStreamHttp can stream in using http.

Re. threading, this class is meant to be called from a single ordering

domain / thread that isn't the fidl_thread. None of the public methods are

safe to call from the fidl_thread; also not the destructor.

All methods including the destructor may rely on fidl_thread to make

progress.

Calls to ReadBytes() will block until there's at least 1 byte or the read

times out.

It is only safe to delete the instance from a thread that is not the

fidl_thread.

Protected Members

async::Loop *const fidl_loop_
async_dispatcher_t *const fidl_dispatcher_
const thrd_t fidl_thread_
sys::ComponentContext *const component_context_
Mutex lock_
uint64_t cursor_position_
bool failure_seen_
bool eos_position_known_
uint64_t eos_position_

Public Methods

void ~InStream ()

All sub-classes must retain the property that it's safe to delete this

instance from any thread.

Sub-classes may wish to use FencePostSerial() at the start of their

destructor to ensure that any lambdas previously posted with PostSerial()

are done before any sub-class member vars are destructed.

Defined at line 27 of file ../../src/media/codec/examples/use_media_decoder/in_stream.cc

uint64_t cursor_position ()

The cursor_position() is the byte offset of the current location in the

input data. This starts at 0.

Every successful ReadBytes() advances cursor_position().

This method is not meant to be overridden by sub-classes.

Defined at line 34 of file ../../src/media/codec/examples/use_media_decoder/in_stream.cc

bool eos_position_known ()

Once this starts returning true it'll continue returning true. At the

latest, this will start returning true when ReadBytesComplete() reads less

than the requested amount.

Defined at line 39 of file ../../src/media/codec/examples/use_media_decoder/in_stream.cc

uint64_t eos_position ()

Requires eos_position_known().

Defined at line 44 of file ../../src/media/codec/examples/use_media_decoder/in_stream.cc

zx_status_t ReadBytesShort (uint32_t max_bytes_to_read, uint32_t * bytes_read_out, uint8_t * buffer_out, zx::time just_fail_deadline)

Returns ZX_OK with *bytes_read_out == 0 if the end of input data has been

reached.

If the end of input data has not yet been reached, this blocks until at

least 1 bytes of input data is available, and then returns ZX_OK indicating

at least 1 byte was read. The caller must not expect that the # of bytes

actaully read is necessarily max_bytes_to_read. Especially as the end of

input data is reached, the *bytes_read_out will sometimes be less than

max_bytes_to_read.

When deadline is non-infinite, and the deadline is reached, timeout will

occur before 1 byte is available and ZX_ERR_TIMED_OUT is returned.

buffer_out must be at least max_bytes_to_read in length.

The cursor_position is advanced by *bytes_read_out.

Sub-classes should override ReadBytesInternal, not ReadBytes.

Defined at line 50 of file ../../src/media/codec/examples/use_media_decoder/in_stream.cc

zx_status_t ReadBytesComplete (uint32_t max_bytes_to_read, uint32_t * bytes_read_out, uint8_t * buffer_out, zx::time just_fail_deadline)

Defined at line 75 of file ../../src/media/codec/examples/use_media_decoder/in_stream.cc

zx_status_t ResetToStart (zx::time just_fail_deadline)

Normally a reset like this isn't necessarily optimal vs. just creating a new instance, but in

tests we want the reset to be fast, so we allow instance reset.

This either succeeds with ZX_OK and sets cursor_position() back to 0, or fails with an error.

If the error is ZX_ERR_NOT_SUPPORTED, a sub-class doesn't support ResetToStart(), and any

wrapper InStream wasn't able to avoid calling ResetToStart() on the sub-class.

Defined at line 112 of file ../../src/media/codec/examples/use_media_decoder/in_stream.cc

Protected Methods

void InStream (async::Loop * fidl_loop, thrd_t fidl_thread, sys::ComponentContext * component_context)

Defined at line 12 of file ../../src/media/codec/examples/use_media_decoder/in_stream.cc

void PostToFidlSerial (fit::closure to_run)

Defined at line 102 of file ../../src/media/codec/examples/use_media_decoder/in_stream.cc

void FencePostToFidlSerial ()

Defined at line 107 of file ../../src/media/codec/examples/use_media_decoder/in_stream.cc

zx_status_t ReadBytesInternal (uint32_t max_bytes_to_read, uint32_t * bytes_read_out, uint8_t * buffer_out, zx::time just_fail_deadline)

Sub-classes override ReadBytesInternal() to actually read data. The

sub-class doesn't need to update cursor_position_ since ReadBytes() handles

that.

zx_status_t ResetToStartInternal (zx::time just_fail_deadline)

Defined at line 120 of file ../../src/media/codec/examples/use_media_decoder/in_stream.cc