IOSource reorg.

A bunch of infrastructure work to move IOSource, IOSourceRegistry (now
iosource::Manager) and PktSrc/PktDumper code into iosource/, and over
to a plugin structure.

Other IOSources aren't touched yet, they are still in src/*.

It compiles and does something with a small trace, but that's all I've
tested so far. There are quite certainly a number of problems left, as
well as various TODOs and cleanup; and nothing's cast in stone yet.

Will continue to work on this.

src/iosource/Manager.h

@@ -0,0 +1,75 @@
+// See the file "COPYING" in the main distribution directory for copyright.
+
+#ifndef IOSOURCE_MANAGER_H
+#define IOSOURCE_MANAGER_H
+
+#include <string>
+#include <list>
+
+namespace iosource {
+
+class IOSource;
+class PktSrc;
+class PktDumper;
+
+class Manager {
+public:
+	Manager()	{ call_count = 0; dont_counts = 0; }
+	~Manager();
+
+	// If dont_count is true, this source does not contribute to the
+	// number of IOSources returned by Size().  The effect is that
+	// if all sources but the non-counting ones have gone dry,
+	// processing will shut down.
+	void Register(IOSource* src, bool dont_count = false);
+
+	// This may block for some time.
+	IOSource* FindSoonest(double* ts);
+
+	int Size() const	{ return sources.size() - dont_counts; }
+
+	typedef std::list<PktSrc *> PktSrcList;
+	const PktSrcList& GetPktSrcs() const	{ return pkt_srcs; }
+
+	// Terminate IOSource processing immediately by removing all
+	// sources (and therefore returning a Size() of zero).
+	void Terminate()	{ RemoveAll(); }
+
+	PktSrc* OpenPktSrc(const std::string& path, const std::string& filter, bool is_live);
+	PktDumper* OpenPktDumper(const std::string& path, bool append);
+
+protected:
+	void Register(PktSrc* src);
+
+	// When looking for a source with something to process,
+	// every SELECT_FREQUENCY calls we will go ahead and
+	// block on a select().
+	static const int SELECT_FREQUENCY = 25;
+
+	// Microseconds to wait in an empty select if no source is ready.
+	static const int SELECT_TIMEOUT = 50;
+
+	void RemoveAll();
+
+	unsigned int call_count;
+	int dont_counts;
+
+	struct Source {
+		IOSource* src;
+		int fd_read;
+		int fd_write;
+		int fd_except;
+	};
+
+	typedef std::list<Source*> SourceList;
+	SourceList sources;
+
+	PktSrcList pkt_srcs;
+};
+
+}
+
+extern iosource::Manager* iosource_mgr;
+
+#endif
+