input/curl: move code to AsyncInputStream

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

4 files changed, 410 insertions, 211 deletions

diff --git a/Makefile.am b/Makefile.am
index 913d4bddd..2df5be262 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1032,6 +1032,7 @@ libinput_a_SOURCES = \
 	src/input/InputPlugin.hxx \
 	src/input/TextInputStream.cxx src/input/TextInputStream.hxx \
 	src/input/ThreadInputStream.cxx src/input/ThreadInputStream.hxx \
+	src/input/AsyncInputStream.cxx src/input/AsyncInputStream.hxx \
 	src/input/ProxyInputStream.cxx src/input/ProxyInputStream.hxx \
 	src/input/plugins/RewindInputPlugin.cxx src/input/plugins/RewindInputPlugin.hxx \
 	src/input/plugins/FileInputPlugin.cxx src/input/plugins/FileInputPlugin.hxx
diff --git a/src/input/AsyncInputStream.cxx b/src/input/AsyncInputStream.cxx
new file mode 100644
index 000000000..3f2d3b90f
--- /dev/null
+++ b/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);
+	}
+}
diff --git a/src/input/AsyncInputStream.hxx b/src/input/AsyncInputStream.hxx
new file mode 100644
index 000000000..f72e7465d
--- /dev/null
+++ b/src/input/AsyncInputStream.hxx
@@ -0,0 +1,122 @@
+/*
+ * 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.
+ */
+
+#ifndef MPD_ASYNC_INPUT_STREAM_HXX
+#define MPD_ASYNC_INPUT_STREAM_HXX
+
+#include "InputStream.hxx"
+#include "event/DeferredMonitor.hxx"
+#include "util/CircularBuffer.hxx"
+#include "util/Error.hxx"
+
+/**
+ * Helper class for moving asynchronous (non-blocking) InputStream
+ * implementations to the I/O thread.  Data is being read into a ring
+ * buffer, and that buffer is then consumed by another thread using
+ * the regular #InputStream API.
+ */
+class AsyncInputStream : public InputStream, private DeferredMonitor {
+	enum class SeekState : uint8_t {
+		NONE, SCHEDULED, PENDING
+	};
+
+	CircularBuffer<uint8_t> buffer;
+	const size_t resume_at;
+
+	bool open;
+
+	/**
+	 * Is the connection currently paused?  That happens when the
+	 * buffer was getting too large.  It will be unpaused when the
+	 * buffer is below the threshold again.
+	 */
+	bool paused;
+
+	SeekState seek_state;
+
+	/**
+	 * The #Tag object ready to be requested via
+	 * InputStream::ReadTag().
+	 */
+	Tag *tag;
+
+	offset_type seek_offset;
+
+protected:
+	Error postponed_error;
+
+public:
+	AsyncInputStream(const char *_url,
+			 Mutex &_mutex, Cond &_cond,
+			 void *_buffer, size_t _buffer_size,
+			 size_t _resume_at);
+
+	virtual ~AsyncInputStream();
+
+	/* virtual methods from InputStream */
+	bool Check(Error &error) final;
+	bool IsEOF() final;
+	bool Seek(offset_type new_offset, Error &error) final;
+	Tag *ReadTag() final;
+	bool IsAvailable() final;
+	size_t Read(void *ptr, size_t read_size, Error &error) final;
+
+protected:
+	void SetTag(Tag *_tag);
+
+	void Pause();
+
+	void SetClosed() {
+		open = false;
+	}
+
+	bool IsBufferEmpty() const {
+		return buffer.IsEmpty();
+	}
+
+	gcc_pure
+	size_t GetBufferSpace() const {
+		return buffer.GetSpace();
+	}
+
+	void AppendToBuffer(const void *data, size_t append_size);
+
+	virtual void DoResume() = 0;
+
+	/**
+	 * The actual Seek() implementation.  This virtual method will
+	 * be called from within the I/O thread.  When the operation
+	 * is finished, call SeekDone() to notify the caller.
+	 */
+	virtual void DoSeek(offset_type new_offset) = 0;
+
+	bool IsSeekPending() const {
+		return seek_state == SeekState::PENDING;
+	}
+
+	void SeekDone();
+
+private:
+	void Resume();
+
+	/* virtual methods from DeferredMonitor */
+	void RunDeferred() final;
+};
+
+#endif
diff --git a/src/input/plugins/CurlInputPlugin.cxx b/src/input/plugins/CurlInputPlugin.cxx
index b48512ccb..2450c8754 100644
--- a/src/input/plugins/CurlInputPlugin.cxx
+++ b/src/input/plugins/CurlInputPlugin.cxx
@@ -19,8 +19,8 @@
 
 #include "config.h"
 #include "CurlInputPlugin.hxx"
+#include "../AsyncInputStream.hxx"
 #include "../IcyInputStream.hxx"
-#include "../InputStream.hxx"
 #include "../InputPlugin.hxx"
 #include "config/ConfigGlobal.hxx"
 #include "config/ConfigData.hxx"
@@ -60,7 +60,7 @@ static const size_t CURL_MAX_BUFFERED = 512 * 1024;
  */
 static const size_t CURL_RESUME_AT = 384 * 1024;
 
-struct CurlInputStream final : public InputStream {
+struct CurlInputStream final : public AsyncInputStream {
 	/* some buffers which were passed to libcurl, which we have
 	   too free */
 	char range[32];
@@ -69,39 +69,19 @@ struct CurlInputStream final : public InputStream {
 	/** the curl handles */
 	CURL *easy;
 
-	/**
-	 * A buffer where input_curl_writefunction() appends
-	 * to, and input_curl_read() reads from.
-	 */
-	CircularBuffer<uint8_t> buffer;
-
-	/**
-	 * Is the connection currently paused?  That happens when the
-	 * buffer was getting too large.  It will be unpaused when the
-	 * buffer is below the threshold again.
-	 */
-	bool paused;
-
 	/** error message provided by libcurl */
 	char error_buffer[CURL_ERROR_SIZE];
 
 	/** parser for icy-metadata */
 	IcyInputStream *icy;
 
-	/** the tag object ready to be requested via
-	    InputStream::ReadTag() */
-	Tag *tag;
-
-	Error postponed_error;
-
 	CurlInputStream(const char *_url, Mutex &_mutex, Cond &_cond,
 			void *_buffer)
-		:InputStream(_url, _mutex, _cond),
+		:AsyncInputStream(_url, _mutex, _cond,
+				  _buffer, CURL_MAX_BUFFERED,
+				  CURL_RESUME_AT),
 		 request_headers(nullptr),
-		 buffer((uint8_t *)_buffer, CURL_MAX_BUFFERED),
-		 paused(false),
-		 icy(new IcyInputStream(this)),
-		 tag(nullptr) {}
+		 icy(new IcyInputStream(this)) {}
 
 	~CurlInputStream();
 
@@ -133,19 +113,6 @@ struct CurlInputStream final : public InputStream {
 
 	size_t DataReceived(const void *ptr, size_t size);
 
-	void Resume();
-	bool FillBuffer(Error &error);
-
-	/**
-	 * Returns the number of bytes stored in the buffer.
-	 *
-	 * The caller must lock the mutex.
-	 */
-	gcc_pure
-	size_t GetTotalBufferSize() const {
-		return buffer.GetSize();
-	}
-
 	/**
 	 * A HTTP request is finished.
 	 *
@@ -153,22 +120,9 @@ struct CurlInputStream final : public InputStream {
 	 */
 	void RequestDone(CURLcode result, long status);
 
-	/* virtual methods from InputStream */
-	bool Check(Error &error) override;
-
-	bool IsEOF() override {
-		return easy == nullptr && buffer.IsEmpty();
-	}
-
-	Tag *ReadTag() override;
-
-	bool IsAvailable() override {
-		return postponed_error.IsDefined() || easy == nullptr ||
-			!buffer.IsEmpty();
-	}
-
-	size_t Read(void *ptr, size_t size, Error &error) override;
-	bool Seek(offset_type offset, Error &error) override;
+	/* virtual methods from AsyncInputStream */
+	virtual void DoResume() override;
+	virtual void DoSeek(offset_type new_offset) override;
 };
 
 class CurlMulti;
@@ -327,23 +281,24 @@ input_curl_find_request(CURL *easy)
 	return (CurlInputStream *)p;
 }
 
-inline void
-CurlInputStream::Resume()
+void
+CurlInputStream::DoResume()
 {
 	assert(io_thread_inside());
 
-	if (paused) {
-		paused = false;
-		curl_easy_pause(easy, CURLPAUSE_CONT);
+	mutex.unlock();
 
-		if (curl_version_num < 0x072000)
-			/* libcurl older than 7.32.0 does not update
-			   its sockets after curl_easy_pause(); force
-			   libcurl to do it now */
-			curl_multi->ResumeSockets();
+	curl_easy_pause(easy, CURLPAUSE_CONT);
 
-		curl_multi->InvalidateSockets();
-	}
+	if (curl_version_num < 0x072000)
+		/* libcurl older than 7.32.0 does not update
+		   its sockets after curl_easy_pause(); force
+		   libcurl to do it now */
+		curl_multi->ResumeSockets();
+
+	curl_multi->InvalidateSockets();
+
+	mutex.lock();
 }
 
 int
@@ -472,6 +427,7 @@ CurlInputStream::RequestDone(CURLcode result, long status)
 	assert(!postponed_error.IsDefined());
 
 	FreeEasy();
+	AsyncInputStream::SetClosed();
 
 	const ScopeLock protect(mutex);
 
@@ -484,7 +440,9 @@ CurlInputStream::RequestDone(CURLcode result, long status)
 				       status);
 	}
 
-	if (!IsReady())
+	if (IsSeekPending())
+		SeekDone();
+	else if (!IsReady())
 		SetReady();
 }
 
@@ -630,81 +588,16 @@ input_curl_finish(void)
 
 CurlInputStream::~CurlInputStream()
 {
-	delete tag;
-
 	FreeEasyIndirect();
-
-	buffer.Clear();
-	HugeFree(buffer.Write().data, CURL_MAX_BUFFERED);
-}
-
-inline bool
-CurlInputStream::Check(Error &error)
-{
-	bool success = !postponed_error.IsDefined();
-	if (!success) {
-		error = std::move(postponed_error);
-		postponed_error.Clear();
-	}
-
-	return success;
-}
-
-Tag *
-CurlInputStream::ReadTag()
-{
-	Tag *result = tag;
-	tag = nullptr;
-	return result;
-}
-
-inline bool
-CurlInputStream::FillBuffer(Error &error)
-{
-	while (easy != nullptr && buffer.IsEmpty())
-		cond.wait(mutex);
-
-	if (postponed_error.IsDefined()) {
-		error = std::move(postponed_error);
-		postponed_error.Clear();
-		return false;
-	}
-
-	return !buffer.IsEmpty();
-}
-
-size_t
-CurlInputStream::Read(void *ptr, size_t read_size, Error &error)
-{
-	if (!FillBuffer(error))
-		return 0;
-
-	auto r = buffer.Read();
-	if (r.IsEmpty())
-		return 0;
-
-	const size_t nbytes = std::min(read_size, r.size);
-	memcpy(ptr, r.data, nbytes);
-	buffer.Consume(nbytes);
-
-	offset += (InputPlugin::offset_type)nbytes;
-
-	if (paused && GetTotalBufferSize() < CURL_RESUME_AT) {
-		mutex.unlock();
-
-		BlockingCall(io_thread_get(), [this](){
-				Resume();
-			});
-
-		mutex.lock();
-	}
-
-	return nbytes;
 }
 
 inline void
 CurlInputStream::HeaderReceived(const char *name, std::string &&value)
 {
+	if (IsSeekPending())
+		/* don't update metadata while seeking */
+		return;
+
 	if (StringEqualsCaseASCII(name, "accept-ranges")) {
 		/* a stream with icy-metadata is not seekable */
 		if (!icy->IsEnabled())
@@ -716,12 +609,10 @@ CurlInputStream::HeaderReceived(const char *name, std::string &&value)
 	} else if (StringEqualsCaseASCII(name, "icy-name") ||
 		   StringEqualsCaseASCII(name, "ice-name") ||
 		   StringEqualsCaseASCII(name, "x-audiocast-name")) {
-		delete tag;
-
 		TagBuilder tag_builder;
 		tag_builder.AddItem(TAG_NAME, value.c_str());
 
-		tag = tag_builder.CommitNew();
+		SetTag(tag_builder.CommitNew());
 	} else if (StringEqualsCaseASCII(name, "icy-metaint")) {
 		if (icy->IsEnabled())
 			return;
@@ -782,30 +673,15 @@ CurlInputStream::DataReceived(const void *ptr, size_t received_size)
 
 	const ScopeLock protect(mutex);
 
-	if (received_size > buffer.GetSpace()) {
-		paused = true;
-		return CURL_WRITEFUNC_PAUSE;
-	}
-
-	auto w = buffer.Write();
-	assert(!w.IsEmpty());
-
-	size_t nbytes = std::min(w.size, received_size);
-	memcpy(w.data, ptr, nbytes);
-	buffer.Append(nbytes);
-
-	const size_t remaining = received_size - nbytes;
-	if (remaining > 0) {
-		w = buffer.Write();
-		assert(!w.IsEmpty());
-		assert(w.size >= remaining);
+	if (IsSeekPending())
+		SeekDone();
 
-		memcpy(w.data, (const uint8_t *)ptr + nbytes, remaining);
-		buffer.Append(remaining);
+	if (received_size > GetBufferSpace()) {
+		AsyncInputStream::Pause();
+		return CURL_WRITEFUNC_PAUSE;
 	}
 
-	ready = true;
-	cond.broadcast();
+	AppendToBuffer(ptr, received_size);
 	return received_size;
 }
 
@@ -880,48 +756,16 @@ CurlInputStream::InitEasy(Error &error)
 	return true;
 }
 
-inline bool
-CurlInputStream::Seek(offset_type new_offset, Error &error)
+void
+CurlInputStream::DoSeek(offset_type new_offset)
 {
 	assert(IsReady());
 
-	if (new_offset == offset)
-		/* no-op */
-		return true;
-
-	if (!IsSeekable())
-		return false;
-
-	/* calculate the absolute offset */
-
-	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 < (InputPlugin::offset_type)r.size
-						   ? new_offset - offset
-						   : r.size;
-
-		buffer.Consume(nbytes);
-		offset += nbytes;
-	}
-
-	if (new_offset == offset)
-		return true;
-
 	/* close the old connection and open a new one */
 
 	mutex.unlock();
 
 	FreeEasyIndirect();
-	buffer.Clear();
 
 	offset = new_offset;
 	if (offset == size) {
@@ -929,12 +773,14 @@ CurlInputStream::Seek(offset_type new_offset, Error &error)
 		   triggering a "416 Requested Range Not Satisfiable"
 		   response */
 		mutex.lock();
-		return true;
+		SeekDone();
+		return;
 	}
 
-	if (!InitEasy(error)) {
+	if (!InitEasy(postponed_error)) {
 		mutex.lock();
-		return false;
+		SeekDone();
+		return;
 	}
 
 	/* send the "Range" header */
@@ -944,23 +790,14 @@ CurlInputStream::Seek(offset_type new_offset, Error &error)
 		curl_easy_setopt(easy, CURLOPT_RANGE, range);
 	}
 
-	ready = false;
-
-	if (!input_curl_easy_add_indirect(this, error)) {
+	if (!input_curl_easy_add_indirect(this, postponed_error)) {
 		mutex.lock();
-		return false;
+		SeekDone();
+		return;
 	}
 
 	mutex.lock();
-	WaitReady();
-
-	if (postponed_error.IsDefined()) {
-		error = std::move(postponed_error);
-		postponed_error.Clear();
-		return false;
-	}
-
-	return true;
+	offset = new_offset;
 }
 
 inline InputStream *