Edit File: my_context.h
/* 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; };