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/*
Copyright (c) 2009-2012 250bpm s.r.o.
Copyright (c) 2007-2009 iMatix Corporation
Copyright (c) 2011 VMware, Inc.
Copyright (c) 2007-2011 Other contributors as noted in the AUTHORS file
This file is part of Crossroads I/O project.
Crossroads I/O is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
Crossroads 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __XS_MSG_HPP_INCLUDE__
#define __XS_MSG_HPP_INCLUDE__
#include <stddef.h>
#include "config.hpp"
#include "atomic_counter.hpp"
// Signature for free function to deallocate the message content.
// Note that it has to be declared as "C" so that it is the same as
// xs_free_fn defined in xs.h.
extern "C"
{
typedef void (msg_free_fn) (void *data, void *hint);
}
namespace xs
{
// Note that this structure needs to be explicitly constructed
// (init functions) and destructed (close function).
class msg_t
{
public:
// Mesage flags.
enum
{
more = 1,
identity = 64,
shared = 128
};
bool check ();
int init ();
int init_size (size_t size_);
int init_data (void *data_, size_t size_, msg_free_fn *ffn_,
void *hint_);
int init_delimiter ();
int close ();
int move (msg_t &src_);
int copy (msg_t &src_);
void *data ();
size_t size ();
unsigned char flags ();
void set_flags (unsigned char flags_);
void reset_flags (unsigned char flags_);
bool is_delimiter ();
bool is_vsm ();
// After calling this function you can copy the message in POD-style
// refs_ times. No need to call copy.
void add_refs (int refs_);
// Removes references previously added by add_refs. If the number of
// references drops to 0, the message is closed and false is returned.
bool rm_refs (int refs_);
private:
// Size in bytes of the largest message that is still copied around
// rather than being reference-counted.
enum {max_vsm_size = 29};
// Shared message buffer. Message data are either allocated in one
// continuous block along with this structure - thus avoiding one
// malloc/free pair or they are stored in used-supplied memory.
// In the latter case, ffn member stores pointer to the function to be
// used to deallocate the data. If the buffer is actually shared (there
// are at least 2 references to it) refcount member contains number of
// references.
struct content_t
{
void *data;
size_t size;
msg_free_fn *ffn;
void *hint;
xs::atomic_counter_t refcnt;
};
// Different message types.
enum type_t
{
type_min = 101,
type_vsm = 101,
type_lmsg = 102,
type_delimiter = 103,
type_max = 103
};
// Note that fields shared between different message types are not
// moved to tha parent class (msg_t). This way we ger tighter packing
// of the data. Shared fields can be accessed via 'base' member of
// the union.
union {
struct {
unsigned char unused [max_vsm_size + 1];
unsigned char type;
unsigned char flags;
} base;
struct {
unsigned char data [max_vsm_size];
unsigned char size;
unsigned char type;
unsigned char flags;
} vsm;
struct {
content_t *content;
unsigned char unused [max_vsm_size + 1 - sizeof (content_t*)];
unsigned char type;
unsigned char flags;
} lmsg;
struct {
unsigned char unused [max_vsm_size + 1];
unsigned char type;
unsigned char flags;
} delimiter;
} u;
};
}
#endif
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