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/*
Copyright 2011 Kristian Nielsen and Monty Program Ab
This file 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 2.1 of the License, or (at your option) any later version.
This library 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 General Public License
along with this. If not, see <http://www.gnu.org/licenses/>.
*/
/*
Simple API for spawning a co-routine, to be used for async libmysqlclient.
Idea is that by implementing this interface using whatever facilities are
available for given platform, we can use the same code for the generic
libmysqlclient-async code.
(This particular implementation uses Posix ucontext swapcontext().)
*/
#ifdef __WIN__
#define MY_CONTEXT_USE_WIN32_FIBERS 1
#elif defined(__GNUC__) && __GNUC__ >= 3 && defined(__x86_64__) && !defined(__ILP32__)
#define MY_CONTEXT_USE_X86_64_GCC_ASM
#elif defined(__GNUC__) && __GNUC__ >= 3 && defined(__i386__)
#define MY_CONTEXT_USE_I386_GCC_ASM
#elif defined(HAVE_UCONTEXT_H)
#define MY_CONTEXT_USE_UCONTEXT
#else
#define MY_CONTEXT_DISABLE
#endif
#ifdef MY_CONTEXT_USE_WIN32_FIBERS
struct my_context {
void (*user_func)(void *);
void *user_arg;
void *app_fiber;
void *lib_fiber;
int return_value;
#ifndef DBUG_OFF
void *dbug_state;
#endif
};
#endif
#ifdef MY_CONTEXT_USE_UCONTEXT
#if defined(__APPLE__) && !defined(_XOPEN_SOURCE)
#define _XOPEN_SOURCE
#endif
#include <ucontext.h>
struct my_context {
void (*user_func)(void *);
void *user_data;
void *stack;
size_t stack_size;
ucontext_t base_context;
ucontext_t spawned_context;
int active;
#ifdef HAVE_VALGRIND_MEMCHECK_H
unsigned int valgrind_stack_id;
#endif
#ifndef DBUG_OFF
void *dbug_state;
#endif
};
#endif
#ifdef MY_CONTEXT_USE_X86_64_GCC_ASM
#include <stdint.h>
struct my_context {
uint64_t save[9];
void *stack_top;
void *stack_bot;
#ifdef HAVE_VALGRIND_MEMCHECK_H
unsigned int valgrind_stack_id;
#endif
#ifndef DBUG_OFF
void *dbug_state;
#endif
};
#endif
#ifdef MY_CONTEXT_USE_I386_GCC_ASM
#include <stdint.h>
struct my_context {
uint64_t save[7];
void *stack_top;
void *stack_bot;
#ifdef HAVE_VALGRIND_MEMCHECK_H
unsigned int valgrind_stack_id;
#endif
#ifndef DBUG_OFF
void *dbug_state;
#endif
};
#endif
#ifdef MY_CONTEXT_DISABLE
struct my_context {
int dummy;
};
#endif
/*
Initialize an asynchroneous context object.
Returns 0 on success, non-zero on failure.
*/
extern int my_context_init(struct my_context *c, size_t stack_size);
/* Free an asynchroneous context object, deallocating any resources used. */
extern void my_context_destroy(struct my_context *c);
/*
Spawn an asynchroneous context. The context will run the supplied user
function, passing the supplied user data pointer.
The context must have been initialised with my_context_init() prior to
this call.
The user function may call my_context_yield(), which will cause this
function to return 1. Then later my_context_continue() may be called, which
will resume the asynchroneous context by returning from the previous
my_context_yield() call.
When the user function returns, this function returns 0.
In case of error, -1 is returned.
*/
extern int my_context_spawn(struct my_context *c, void (*f)(void *), void *d);
/*
Suspend an asynchroneous context started with my_context_spawn.
When my_context_yield() is called, execution immediately returns from the
last my_context_spawn() or my_context_continue() call. Then when later
my_context_continue() is called, execution resumes by returning from this
my_context_yield() call.
Returns 0 if ok, -1 in case of error.
*/
extern int my_context_yield(struct my_context *c);
/*
Resume an asynchroneous context. The context was spawned by
my_context_spawn(), and later suspended inside my_context_yield().
The asynchroneous context may be repeatedly suspended with
my_context_yield() and resumed with my_context_continue().
Each time it is suspended, this function returns 1. When the originally
spawned user function returns, this function returns 0.
In case of error, -1 is returned.
*/
extern int my_context_continue(struct my_context *c);
struct mysql_async_context {
/*
This is set to the value that should be returned from foo_start() or
foo_cont() when a call is suspended.
*/
unsigned int events_to_wait_for;
/*
It is also set to the event(s) that triggered when a suspended call is
resumed, eg. whether we woke up due to connection completed or timeout
in mysql_real_connect_cont().
*/
unsigned int events_occurred;
/*
This is set to the result of the whole asynchronous operation when it
completes. It uses a union, as different calls have different return
types.
*/
union {
void *r_ptr;
const void *r_const_ptr;
int r_int;
my_bool r_my_bool;
} ret_result;
/*
The timeout value (in millisecods), for suspended calls that need to wake
up on a timeout (eg. mysql_real_connect_start().
*/
unsigned int timeout_value;
/*
This flag is set when we are executing inside some asynchronous call
foo_start() or foo_cont(). It is used to decide whether to use the
synchronous or asynchronous version of calls that may block such as
recv().
Note that this flag is not set when a call is suspended, eg. after
returning from foo_start() and before re-entering foo_cont().
*/
my_bool active;
/*
This flag is set when an asynchronous operation is in progress, but
suspended. Ie. it is set when foo_start() or foo_cont() returns because
the operation needs to block, suspending the operation.
It is used to give an error (rather than crash) if the application
attempts to call some foo_cont() method when no suspended operation foo is
in progress.
*/
my_bool suspended;
/*
If non-NULL, this is a pointer to a callback hook that will be invoked with
the user data argument just before the context is suspended, and just after
it is resumed.
*/
void (*suspend_resume_hook)(my_bool suspend, void *user_data);
void *suspend_resume_hook_user_data;
/*
This is used to save the execution contexts so that we can suspend an
operation and switch back to the application context, to resume the
suspended context later when the application re-invokes us with
foo_cont().
*/
struct my_context async_context;
};
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