1 /*
2  * Copyright (C) 1998-2015 Paul Davis <paul@linuxaudiosystems.com>
3  * Copyright (C) 2009-2014 David Robillard <d@drobilla.net>
4  * Copyright (C) 2010 Carl Hetherington <carl@carlh.net>
5  * Copyright (C) 2015-2017 Robin Gareus <robin@gareus.org>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License along
18  * with this program; if not, write to the Free Software Foundation, Inc.,
19  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
20  */
21 
22 #ifndef __qm_pool_h__
23 #define __qm_pool_h__
24 
25 #include <vector>
26 #include <string>
27 
28 #include <glibmm/threads.h>
29 
30 #include "pbd/libpbd_visibility.h"
31 #include "pbd/ringbuffer.h"
32 
33 /** A pool of data items that can be allocated, read from and written to
34  *  without system memory allocation or locking.
35  */
36 class LIBPBD_API Pool
37 {
38   public:
39 	Pool (std::string name, unsigned long item_size, unsigned long nitems);
40 	virtual ~Pool ();
41 
42 	virtual void *alloc ();
43 	virtual void release (void *);
44 
name()45 	std::string name() const { return _name; }
available()46 	guint available() const { return free_list.read_space(); }
used()47 	guint used() const { return free_list.bufsize() - available(); }
total()48 	guint total() const { return free_list.bufsize(); }
49 
50   protected:
51 	PBD::RingBuffer<void*> free_list; ///< a list of pointers to free items within block
52 	std::string _name;
53 
54   private:
55 	void *block; ///< data storage area
56 #ifndef NDEBUG
57 	unsigned long max_usage;
58 #endif
59 };
60 
61 class LIBPBD_API SingleAllocMultiReleasePool : public Pool
62 {
63   public:
64 	SingleAllocMultiReleasePool (std::string name, unsigned long item_size, unsigned long nitems);
65 	~SingleAllocMultiReleasePool ();
66 
67 	virtual void *alloc ();
68 	virtual void release (void *);
69 
70   private:
71         Glib::Threads::Mutex m_lock;
72 };
73 
74 
75 class LIBPBD_API MultiAllocSingleReleasePool : public Pool
76 {
77   public:
78 	MultiAllocSingleReleasePool (std::string name, unsigned long item_size, unsigned long nitems);
79 	~MultiAllocSingleReleasePool ();
80 
81 	virtual void *alloc ();
82 	virtual void release (void *);
83 
84   private:
85         Glib::Threads::Mutex m_lock;
86 };
87 
88 class LIBPBD_API PerThreadPool;
89 
90 /** Management of a per-thread pool of data that is allocated by one thread and
91  *  freed by one other thread. Not safe for use when there is more than 1
92  *  reader and 1 writer.
93  *
94  *  This is basically a wrapper around a thread-local storage instance of a
95  *  ringbuffer, made safe for use in the case where multiple threads allocate
96  *  from the ringbuffer and a single thread "frees" the allocations.
97  *
98  *  Rather than using locks, each thread has its own ringbuffer (and associated
99  *  data), and so it calls alloc(), passes a pointer to the result of the alloc
100  *  to another thread, which later calls push() to "free" it.
101  */
102 class LIBPBD_API CrossThreadPool : public Pool
103 {
104   public:
105 	CrossThreadPool (std::string n, unsigned long isize, unsigned long nitems, PerThreadPool *);
106 
107 	void* alloc ();
108 	void push (void *);
109 
parent()110 	PerThreadPool* parent () const {
111 		return _parent;
112 	}
113 
114 	bool empty ();
pending_size()115 	guint pending_size() const { return pending.read_space(); }
116 
117 	void flush_pending ();
118 	void flush_pending_with_ev (void*);
119 
120   private:
121 	PBD::RingBuffer<void*> pending;
122 	PerThreadPool* _parent;
123 };
124 
125 /** A class to manage per-thread pools of memory.  One object of this class is instantiated,
126  *  and then it is used to create per-thread pools for 1 or more threads as required.
127  */
128 class LIBPBD_API PerThreadPool
129 {
130 public:
131 	PerThreadPool ();
132 
key()133 	const Glib::Threads::Private<CrossThreadPool>& key() const { return _key; }
134 
135 	void  create_per_thread_pool (std::string name, unsigned long item_size, unsigned long nitems);
136 	CrossThreadPool* per_thread_pool (bool must_exist = true);
137 	bool has_per_thread_pool ();
138 	void set_trash (PBD::RingBuffer<CrossThreadPool*>* t);
139 	void add_to_trash (CrossThreadPool *);
140 
141 private:
142 	Glib::Threads::Private<CrossThreadPool> _key;
143 	std::string _name;
144 
145 	/** mutex to protect either changes to the _trash variable, or writes to the RingBuffer */
146 	Glib::Threads::Mutex _trash_mutex;
147 	PBD::RingBuffer<CrossThreadPool*>* _trash;
148 };
149 
150 #endif // __qm_pool_h__
151