Improve convenience of the Channel API.

- allows all methods to be called on a `shared(Channel!T)` instance.
- `Channel` pre-defines the `buffer_size` argument to 100, matching `createChannel`

source/vibe/core/channel.d

@@ -34,7 +34,7 @@ Channel!(T, buffer_size) createChannel(T, size_t buffer_size = 100)()
 	The implementation supports multiple-reader-multiple-writer operation across
 	multiple tasks in multiple threads.
 */
-struct Channel(T, size_t buffer_size) {
+struct Channel(T, size_t buffer_size = 100) {
 	enum bufferSize = buffer_size;
 
 	private shared ChannelImpl!(T, buffer_size) m_impl;
@@ -51,6 +51,8 @@ struct Channel(T, size_t buffer_size) {
 		`tryConsumeOne` in a multiple-reader scenario instead.
 	*/
 	@property bool empty() { return m_impl.empty; }
+	/// ditto
+	@property bool empty() shared { return m_impl.empty; }
 
 	/** Closes the channel.
 
@@ -59,6 +61,8 @@ struct Channel(T, size_t buffer_size) {
 		been consumed.
 	*/
 	void close() { m_impl.close(); }
+	/// ditto
+	void close() shared { m_impl.close(); }
 
 	/** Consumes a single element off the queue.
 
@@ -66,6 +70,8 @@ struct Channel(T, size_t buffer_size) {
 		property is `true`, an exception will be thrown.
 	*/
 	T consumeOne() { return m_impl.consumeOne(); }
+	/// ditto
+	T consumeOne() shared { return m_impl.consumeOne(); }
 
 	/** Attempts to consume a single element.
 
@@ -73,6 +79,8 @@ struct Channel(T, size_t buffer_size) {
 		`false` is returned and `dst` is left untouched.
 	*/
 	bool tryConsumeOne(ref T dst) { return m_impl.tryConsumeOne(dst); }
+	/// ditto
+	bool tryConsumeOne(ref T dst) shared { return m_impl.tryConsumeOne(dst); }
 
 	/** Attempts to consume all elements currently in the queue.
 
@@ -86,12 +94,18 @@ struct Channel(T, size_t buffer_size) {
 	bool consumeAll(ref FixedRingBuffer!(T, buffer_size) dst)
 		in { assert(dst.empty); }
 		body { return m_impl.consumeAll(dst); }
+	/// ditto
+	bool consumeAll(ref FixedRingBuffer!(T, buffer_size) dst) shared
+		in { assert(dst.empty); }
+		body { return m_impl.consumeAll(dst); }
 
 	/** Enqueues an element.
 
 		This function may block the the event that the internal buffer is full.
 	*/
 	void put(T item) { m_impl.put(item.move); }
+	/// ditto
+	void put(T item) shared { m_impl.put(item.move); }
 }
 
 
@@ -235,3 +249,12 @@ unittest { // test basic operation and non-copyable struct compatiblity
 	assert(ch.empty);
 	assert(!ch.tryConsumeOne(v));
 }
+
+unittest { // make sure shared(Channel!T) can also be used
+	shared ch = createChannel!int;
+	ch.put(1);
+	assert(!ch.empty);
+	assert(ch.consumeOne == 1);
+	ch.close();
+	assert(ch.empty);
+}