input/curl: move code to AsyncInputStream

New base class for other InputStream implementations that run in the
I/O thread.

src/input/AsyncInputStream.cxx

@@ -0,0 +1,239 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "AsyncInputStream.hxx"
+#include "tag/Tag.hxx"
+#include "event/Call.hxx"
+#include "thread/Cond.hxx"
+#include "IOThread.hxx"
+#include "util/HugeAllocator.hxx"
+
+#include <assert.h>
+#include <string.h>
+
+AsyncInputStream::AsyncInputStream(const char *_url,
+				   Mutex &_mutex, Cond &_cond,
+				   void *_buffer, size_t _buffer_size,
+				   size_t _resume_at)
+	:InputStream(_url, _mutex, _cond), DeferredMonitor(io_thread_get()),
+	 buffer((uint8_t *)_buffer, _buffer_size),
+	 resume_at(_resume_at),
+	 open(true),
+	 paused(false),
+	 seek_state(SeekState::NONE),
+	 tag(nullptr) {}
+
+AsyncInputStream::~AsyncInputStream()
+{
+	delete tag;
+
+	buffer.Clear();
+	HugeFree(buffer.Write().data, buffer.GetCapacity());
+}
+
+void
+AsyncInputStream::SetTag(Tag *_tag)
+{
+	delete tag;
+	tag = _tag;
+}
+
+void
+AsyncInputStream::Pause()
+{
+	assert(io_thread_inside());
+
+	paused = true;
+}
+
+inline void
+AsyncInputStream::Resume()
+{
+	assert(io_thread_inside());
+
+	if (paused) {
+		paused = false;
+		DoResume();
+	}
+}
+
+bool
+AsyncInputStream::Check(Error &error)
+{
+	bool success = !postponed_error.IsDefined();
+	if (!success) {
+		error = std::move(postponed_error);
+		postponed_error.Clear();
+	}
+
+	return success;
+}
+
+bool
+AsyncInputStream::IsEOF()
+{
+	return !open && buffer.IsEmpty();
+}
+
+bool
+AsyncInputStream::Seek(offset_type new_offset, Error &error)
+{
+	assert(IsReady());
+	assert(seek_state == SeekState::NONE);
+
+	if (new_offset == offset)
+		/* no-op */
+		return true;
+
+	if (!IsSeekable())
+		return false;
+
+	if (new_offset < 0)
+		return false;
+
+	/* check if we can fast-forward the buffer */
+
+	while (new_offset > offset) {
+		auto r = buffer.Read();
+		if (r.IsEmpty())
+			break;
+
+		const size_t nbytes =
+			new_offset - offset < (offset_type)r.size
+					       ? new_offset - offset
+					       : r.size;
+
+		buffer.Consume(nbytes);
+		offset += nbytes;
+	}
+
+	if (new_offset == offset)
+		return true;
+
+	/* no: ask the implementation to seek */
+
+	seek_offset = new_offset;
+	seek_state = SeekState::SCHEDULED;
+
+	DeferredMonitor::Schedule();
+
+	while (seek_state != SeekState::NONE)
+		cond.wait(mutex);
+
+	if (!Check(error))
+		return false;
+
+	return true;
+}
+
+void
+AsyncInputStream::SeekDone()
+{
+	assert(io_thread_inside());
+	assert(IsSeekPending());
+
+	seek_state = SeekState::NONE;
+	cond.broadcast();
+}
+
+Tag *
+AsyncInputStream::ReadTag()
+{
+	Tag *result = tag;
+	tag = nullptr;
+	return result;
+}
+
+bool
+AsyncInputStream::IsAvailable()
+{
+	return postponed_error.IsDefined() || !open ||
+		!buffer.IsEmpty();
+}
+
+size_t
+AsyncInputStream::Read(void *ptr, size_t read_size, Error &error)
+{
+	assert(!io_thread_inside());
+
+	/* wait for data */
+	CircularBuffer<uint8_t>::Range r;
+	while (true) {
+		if (!Check(error))
+			return 0;
+
+		r = buffer.Read();
+		if (!r.IsEmpty() || !open)
+			break;
+
+		cond.wait(mutex);
+	}
+
+	const size_t nbytes = std::min(read_size, r.size);
+	memcpy(ptr, r.data, nbytes);
+	buffer.Consume(nbytes);
+
+	offset += (offset_type)nbytes;
+
+	if (paused && buffer.GetSize() < resume_at)
+		DeferredMonitor::Schedule();
+
+	return nbytes;
+}
+
+void
+AsyncInputStream::AppendToBuffer(const void *data, size_t append_size)
+{
+	auto w = buffer.Write();
+	assert(!w.IsEmpty());
+
+	size_t nbytes = std::min(w.size, append_size);
+	memcpy(w.data, data, nbytes);
+	buffer.Append(nbytes);
+
+	const size_t remaining = append_size - nbytes;
+	if (remaining > 0) {
+		w = buffer.Write();
+		assert(!w.IsEmpty());
+		assert(w.size >= remaining);
+
+		memcpy(w.data, (const uint8_t *)data + nbytes, remaining);
+		buffer.Append(remaining);
+	}
+
+	if (!IsReady())
+		SetReady();
+	else
+		cond.broadcast();
+}
+
+void
+AsyncInputStream::RunDeferred()
+{
+	const ScopeLock protect(mutex);
+
+	Resume();
+
+	if (seek_state == SeekState::SCHEDULED) {
+		seek_state = SeekState::PENDING;
+		buffer.Clear();
+		DoSeek(seek_offset);
+	}
+}