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experiment with WIN_THREAD_CONTEXT

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This commit is contained in:
David Rose 2010-04-27 21:30:08 +00:00
parent 33276672f3
commit 15d98ead96
12 changed files with 711 additions and 458 deletions
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2
panda/src/pipeline/Sources.pp
View File

@ -85,6 +85,8 @@
conditionVarSimpleImpl.cxx \
conditionVarSpinlockImpl.cxx \
config_pipeline.cxx \
contextSwitch_longjmp_src.c contextSwitch_ucontext_src.c \
contextSwitch_windows_src.c \
cycleData.cxx \
cycleDataLockedReader.cxx \
cycleDataLockedStageReader.cxx \

426
panda/src/pipeline/contextSwitch.c
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@ -17,418 +17,26 @@
#include <stdlib.h>
#include <stdio.h>
#ifdef THREAD_SIMPLE_IMPL
#if defined(THREAD_SIMPLE_IMPL) && !defined(CPPPARSER)
#if defined(PHAVE_UCONTEXT_H)
#ifdef WIN32
/* Define this macro to use native Windows threading constructs to
switch contexts. */
#define WIN_THREAD_CONTEXT
#endif
#else /* PHAVE_UCONTEXT_H */
#if defined(WIN_THREAD_CONTEXT)
#include "contextSwitch_windows_src.c"
#elif defined(PHAVE_UCONTEXT_H)
#include "contextSwitch_ucontext_src.c"
#else
#include "contextSwitch_longjmp_src.c"
#endif /* PHAVE_UCONTEXT_H */
#if defined(PHAVE_UCONTEXT_H)
/* We'd prefer to use getcontext() / setcontext() to portably change
execution contexts within C code. That's what these library
functions are designed for. */
#ifdef __APPLE__
#include <sys/ucontext.h>
#else
#include <ucontext.h>
#endif
struct ThreadContext {
ucontext_t _ucontext;
#ifdef __APPLE__
// Due to a bug in OSX 10.5, the system ucontext_t declaration
// doesn't reserve enough space, and we need to reserve some
// additional space to make room.
#define EXTRA_PADDING_SIZE 4096
char _extra_padding[EXTRA_PADDING_SIZE];
#endif
};
static void
begin_context(ContextFunction *thread_func, void *data) {
(*thread_func)(data);
}
void
init_thread_context(struct ThreadContext *context,
unsigned char *stack, size_t stack_size,
ContextFunction *thread_func, void *data) {
if (getcontext(&context->_ucontext) != 0) {
fprintf(stderr, "getcontext failed in init_thread_context!\n");
// Too bad for you.
abort();
}
context->_ucontext.uc_stack.ss_sp = stack;
context->_ucontext.uc_stack.ss_size = stack_size;
context->_ucontext.uc_stack.ss_flags = 0;
context->_ucontext.uc_link = NULL;
makecontext(&context->_ucontext, (void (*)())&begin_context, 2, thread_func, data);
}
void
save_thread_context(struct ThreadContext *context,
ContextFunction *next_context, void *data) {
/* getcontext requires us to use a volatile auto variable to
differentiate between pass 1 (immediate return) and pass 2
(return from setcontext). */
volatile int context_return = 0;
if (getcontext(&context->_ucontext) != 0) {
fprintf(stderr, "getcontext failed!\n");
// Nothing to do here.
abort();
}
if (context_return) {
/* We have just returned from setcontext. In this case, return
from the function. The stack is still good. */
return;
}
context_return = 1;
/* We are still in the calling thread. In this case, we cannot
return from the function without damaging the stack. Insted,
call next_context() and trust the caller to call
switch_to_thread_context() in there somewhere. */
(*next_context)(data);
/* We shouldn't get here. */
abort();
}
void
switch_to_thread_context(struct ThreadContext *context) {
setcontext(&context->_ucontext);
/* Shouldn't get here. */
abort();
}
#else
/* Unfortunately, setcontext() is not defined everywhere (even though
it claims to be adopted by Posix). So we have to fall back to
setjmp() / longjmp() in its absence. This is a hackier solution. */
#if defined(_M_IX86) || defined(__i386__)
/* Maybe we can implement our own setjmp/longjmp in assembly code.
This will be safer than the system version, since who knows what
that one's really doing? */
typedef int cs_jmp_buf[33];
#define CS_JB_SP 4
#else
/* Fall back to the system implmentation of setjmp/longjmp. */
#include <setjmp.h>
typedef jmp_buf cs_jmp_buf;
#define cs_setjmp setjmp
#define cs_longjmp(buf) longjmp(buf, 1)
#ifdef JB_SP
#define CS_JB_SP JB_SP
#elif defined(__ppc__)
/* This was determined experimentally through test_setjmp. */
#define CS_JB_SP 0
#endif
#endif /* __i386__ */
struct ThreadContext {
cs_jmp_buf _jmp_context;
};
/* The approach is: hack our way onto the new stack pointer right now,
then call setjmp() to record that stack pointer in the
_jmp_context. Then restore back to the original stack pointer. */
#if defined(_M_IX86)
/* Here is our own implementation of setjmp and longjmp for I386, via
Windows syntax. */
/* warning C4731: frame pointer register 'ebp' modified by inline assembly code */
#pragma warning(disable:4731)
int
cs_setjmp(cs_jmp_buf env) {
__asm {
pop ebp; /* Restore the frame pointer that the compiler pushed */
pop edx; /* edx = return address */
pop eax; /* eax = &env */
push eax; /* keep &env on the stack; the caller will remove it */
mov [eax + 0], ebx;
mov [eax + 4], edi;
mov [eax + 8], esi;
mov [eax + 12], ebp;
mov [eax + 16], esp;
mov [eax + 20], edx;
fnsave [eax + 24]; /* save floating-point state */
xor eax,eax; /* return 0: pass 1 return */
jmp edx; /* this works like ret */
}
}
void
cs_longjmp(cs_jmp_buf env) {
_asm {
mov eax, env;
mov ebx, [eax + 0];
mov edi, [eax + 4];
mov esi, [eax + 8];
mov ebp, [eax + 12];
mov esp, [eax + 16];
mov edx, [eax + 20];
frstor [eax + 24]; /* restore floating-point state */
mov eax, 1; /* return 1 from setjmp: pass 2 return */
jmp edx; /* return from above setjmp call */
}
}
#elif defined(__i386__)
/* Here is our own implementation of setjmp and longjmp for I386, via
GNU syntax. */
#if defined(IS_LINUX)
/* On Linux, the leading underscores are not implicitly added for C
function names. */
#define cs_setjmp _cs_setjmp
#define cs_longjmp _cs_longjmp
#endif
int cs_setjmp(cs_jmp_buf env);
void cs_longjmp(cs_jmp_buf env);
__asm__
("_cs_setjmp:\n"
"popl %edx\n"
"popl %eax\n"
"pushl %eax\n"
"movl %ebx, 0(%eax)\n"
"movl %edi, 4(%eax)\n"
"movl %esi, 8(%eax)\n"
"movl %ebp, 12(%eax)\n"
"movl %esp, 16(%eax)\n"
"movl %edx, 20(%eax)\n"
"fnsave 24(%eax)\n"
"xorl %eax, %eax\n"
"jmp *%edx\n");
__asm__
("_cs_longjmp:\n"
"popl %edx\n"
"popl %eax\n"
"movl 0(%eax), %ebx\n"
"movl 4(%eax), %edi\n"
"movl 8(%eax), %esi\n"
"movl 12(%eax), %ebp\n"
"movl 16(%eax), %esp\n"
"movl 20(%eax), %edx\n"
"frstor 24(%eax)\n"
"mov $1,%eax\n"
"jmp *%edx\n");
#endif /* __i386__ */
/* Ideally, including setjmp.h would have defined JB_SP, which will
tell us where in the context structure we can muck with the stack
pointer. If it didn't define this symbol, we have to guess it. */
#ifndef CS_JB_SP
#if defined(IS_OSX) && defined(__i386__)
/* We have determined this value empirically, via test_setjmp.cxx in
this directory. */
#define CS_JB_SP 9
#endif
#endif /* CS_JB_SP */
static struct ThreadContext *st_context;
static unsigned char *st_stack;
static size_t st_stack_size;
static ContextFunction *st_thread_func;
static void *st_data;
static cs_jmp_buf orig_stack;
/* We can't declare this function static--gcc might want to inline it
in that case, and then the code crashes. I hope this doesn't mean
that the stack is still not getting restored correctly in the above
assembly code. */
void
setup_context_2(void) {
/* Here we are running on the new stack. Copy the key data onto our
new stack. */
ContextFunction *volatile thread_func = st_thread_func;
void *volatile data = st_data;
if (cs_setjmp(st_context->_jmp_context) == 0) {
/* The _jmp_context is set up and ready to run. Now restore the
original stack and return. We can't simply return from this
function, since it might overwrite some of the stack data on
the way out. */
cs_longjmp(orig_stack);
/* Shouldn't get here. */
abort();
}
/* We come here the first time the thread starts. */
(*thread_func)(data);
/* We shouldn't get here, since we don't expect the thread_func to
return. */
abort();
}
static void
setup_context_1(void) {
/* Save the current stack frame so we can return to it (at the end
of setup_context_2()). */
if (cs_setjmp(orig_stack) == 0) {
/* First, switch to the new stack. Save the current context using
setjmp(). This saves out all of the processor register values,
though it doesn't muck with the stack. */
static cs_jmp_buf temp;
if (cs_setjmp(temp) == 0) {
/* This is the initial return from setjmp. Still the original
stack. */
/* Now we overwrite the stack pointer value in the saved
register context. This doesn't work with all implementations
of setjmp/longjmp. */
/* We give ourselves a small buffer of unused space at the top
of the stack, to allow for the stack frame and such that this
code might be assuming is there. */
(*(void **)&temp[CS_JB_SP]) = (st_stack + st_stack_size - 0x100);
/* And finally, we place ourselves on the new stack by using
longjmp() to reload the modified context. */
cs_longjmp(temp);
/* Shouldn't get here. */
abort();
}
/* This is the second return from setjmp. Now we're on the new
stack. */
setup_context_2();
/* Shouldn't get here. */
abort();
}
/* By now we are back to the original stack. */
}
void
init_thread_context(struct ThreadContext *context,
unsigned char *stack, size_t stack_size,
ContextFunction *thread_func, void *data) {
/* Copy all of the input parameters to static variables, then begin
the stack-switching process. */
st_context = context;
st_stack = stack;
st_stack_size = stack_size;
st_thread_func = thread_func;
st_data = data;
setup_context_1();
}
void
save_thread_context(struct ThreadContext *context,
ContextFunction *next_context, void *data) {
if (cs_setjmp(context->_jmp_context) != 0) {
/* We have just returned from longjmp. In this case, return from
the function. The stack is still good. */
return;
}
/* We are still in the calling thread. In this case, we cannot
return from the function without damaging the stack. Insted,
call next_context() and trust the caller to call
switch_to_thread_context() in there somewhere. */
(*next_context)(data);
/* We shouldn't get here. */
abort();
}
void
switch_to_thread_context(struct ThreadContext *context) {
cs_longjmp(context->_jmp_context);
/* Shouldn't get here. */
abort();
}
#endif /* PHAVE_UCONTEXT_H */
struct ThreadContext *
alloc_thread_context() {
struct ThreadContext *context =
(struct ThreadContext *)malloc(sizeof(struct ThreadContext));
#if defined(__APPLE__) && defined(_DEBUG)
{
int p;
// Pre-fill the extra_padding with bytes that we can recognize
// later.
for (p = 0; p < EXTRA_PADDING_SIZE; ++p) {
context->_extra_padding[p] = (p & 0xff);
}
}
#endif // __APPLE__
return context;
}
void
free_thread_context(struct ThreadContext *context) {
#if defined(__APPLE__) && defined(_DEBUG)
{
// Because of the OSX 10.5 bug, we anticipate that the extra_padding
// may have been filled in with junk. Confirm this.
int p = EXTRA_PADDING_SIZE;
while (p > 0) {
--p;
if (context->_extra_padding[p] != (char)(p & 0xff)) {
fprintf(stderr, "Context was mangled at byte %d: %d!\n", p, context->_extra_padding[p]);
break;
}
}
}
#endif // __APPLE__
free(context);
}
#endif /* THREAD_SIMPLE_IMPL */

35
panda/src/pipeline/contextSwitch.h
View File

@ -36,16 +36,21 @@ struct ThreadContext;
extern "C" {
#endif
typedef void ContextFunction(void *);
typedef void ContextFunction(struct ThreadContext *from_context, void *);
typedef void ThreadFunction(void *);
/* Call this to fill in the appropriate values in context. The stack
must already have been allocated. The context will be initialized
so that when switch_to_thread_context() is called, it will begin
executing thread_func(data), which should not return. This function
will return normally. */
extern const int needs_stack_prealloc;
/* Call this to fill in the appropriate values in context. If
needs_stack_prealloc (above) is true, the stack must already have
been allocated; if needs_stack_prealloc is false, the stack pointer
is not used and may be NULL. The context will be initialized so
that when switch_to_thread_context() is called, it will begin
executing thread_func(data), which should not return. This
function will return normally. */
void init_thread_context(struct ThreadContext *context,
unsigned char *stack, size_t stack_size,
ContextFunction *thread_func, void *data);
ThreadFunction *thread_func, void *data);
/* Call this to save the current thread context. This function does
not return until switch_to_thread_context() is called. Instead it
@ -53,15 +58,19 @@ void init_thread_context(struct ThreadContext *context,
void save_thread_context(struct ThreadContext *context,
ContextFunction *next_context, void *data);
/* Call this to resume executing a previously saved context. When
called, it will return from save_thread_context() in the saved
stack (or begin executing thread_func()). */
void switch_to_thread_context(struct ThreadContext *context);
/* Call this to resume executing a previously saved context.
from_context must be the currently-executing context, and
to_context is the context to resume. When called, it will return
from save_thread_context() in the saved stack (or begin executing
thread_func()). */
void switch_to_thread_context(struct ThreadContext *from_context,
struct ThreadContext *to_context);
/* Use this pair of functions to transparently allocate and destroy an
opaque ThreadContext object of the appropriate size. These
functions only allocate memory; they do not initialize the values
of the context (see init_thread_context(), above, for that). */
functions allocate memory, and initialize the context as
appropriate for the main thread. See init_main_context() to finish
the initialization for a new thread. */
struct ThreadContext *alloc_thread_context();
void free_thread_context(struct ThreadContext *context);

308
panda/src/pipeline/contextSwitch_longjmp_src.c Executable file
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@ -0,0 +1,308 @@
/* Filename: contextSwitch_longjmp_src.c
* Created by: drose (15Apr10)
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* PANDA 3D SOFTWARE
* Copyright (c) Carnegie Mellon University. All rights reserved.
*
* All use of this software is subject to the terms of the revised BSD
* license. You should have received a copy of this license along
* with this source code in a file named "LICENSE."
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/* This is the implementation of user-space context switching using
setmp() / longjmp(). This is the hackier implementation,
which is necessary if setcontext() is not available. */
const int needs_stack_prealloc = 1;
#if defined(_M_IX86) || defined(__i386__)
/* Maybe we can implement our own setjmp/longjmp in assembly code.
This will be safer than the system version, since who knows what
that one's really doing? */
typedef int cs_jmp_buf[33];
#define CS_JB_SP 4
#else
/* Fall back to the system implementation of setjmp/longjmp. */
#include <setjmp.h>
typedef jmp_buf cs_jmp_buf;
#define cs_setjmp setjmp
#define cs_longjmp(buf) longjmp(buf, 1)
#ifdef JB_SP
#define CS_JB_SP JB_SP
#elif defined(__ppc__)
/* This was determined experimentally through test_setjmp. */
#define CS_JB_SP 0
#endif
#endif /* __i386__ */
struct ThreadContext {
cs_jmp_buf _jmp_context;
};
/* The approach is: hack our way onto the new stack pointer right now,
then call setjmp() to record that stack pointer in the
_jmp_context. Then restore back to the original stack pointer. */
#if defined(_M_IX86)
/* Here is our own implementation of setjmp and longjmp for I386, via
Windows syntax. */
/* warning C4731: frame pointer register 'ebp' modified by inline assembly code */
#pragma warning(disable:4731)
int
cs_setjmp(cs_jmp_buf env) {
__asm {
pop ebp; /* Restore the frame pointer that the compiler pushed */
pop edx; /* edx = return address */
pop eax; /* eax = &env */
push eax; /* keep &env on the stack; the caller will remove it */
mov [eax + 0], ebx;
mov [eax + 4], edi;
mov [eax + 8], esi;
mov [eax + 12], ebp;
mov [eax + 16], esp;
mov [eax + 20], edx;
fnsave [eax + 24]; /* save floating-point state */
xor eax,eax; /* return 0: pass 1 return */
jmp edx; /* this works like ret */
}
}
void
cs_longjmp(cs_jmp_buf env) {
_asm {
mov eax, env;
mov ebx, [eax + 0];
mov edi, [eax + 4];
mov esi, [eax + 8];
mov ebp, [eax + 12];
mov esp, [eax + 16];
mov edx, [eax + 20];
frstor [eax + 24]; /* restore floating-point state */
mov eax, 1; /* return 1 from setjmp: pass 2 return */
jmp edx; /* return from above setjmp call */
}
}
#elif defined(__i386__)
/* Here is our own implementation of setjmp and longjmp for I386, via
GNU syntax. */
#if defined(IS_LINUX)
/* On Linux, the leading underscores are not implicitly added for C
function names. */
#define cs_setjmp _cs_setjmp
#define cs_longjmp _cs_longjmp
#endif
int cs_setjmp(cs_jmp_buf env);
void cs_longjmp(cs_jmp_buf env);
__asm__
("_cs_setjmp:\n"
"popl %edx\n"
"popl %eax\n"
"pushl %eax\n"
"movl %ebx, 0(%eax)\n"
"movl %edi, 4(%eax)\n"
"movl %esi, 8(%eax)\n"
"movl %ebp, 12(%eax)\n"
"movl %esp, 16(%eax)\n"
"movl %edx, 20(%eax)\n"
"fnsave 24(%eax)\n"
"xorl %eax, %eax\n"
"jmp *%edx\n");
__asm__
("_cs_longjmp:\n"
"popl %edx\n"
"popl %eax\n"
"movl 0(%eax), %ebx\n"
"movl 4(%eax), %edi\n"
"movl 8(%eax), %esi\n"
"movl 12(%eax), %ebp\n"
"movl 16(%eax), %esp\n"
"movl 20(%eax), %edx\n"
"frstor 24(%eax)\n"
"mov $1,%eax\n"
"jmp *%edx\n");
#endif /* __i386__ */
/* Ideally, including setjmp.h would have defined JB_SP, which will
tell us where in the context structure we can muck with the stack
pointer. If it didn't define this symbol, we have to guess it. */
#ifndef CS_JB_SP
#if defined(IS_OSX) && defined(__i386__)
/* We have determined this value empirically, via test_setjmp.cxx in
this directory. */
#define CS_JB_SP 9
#endif
#endif /* CS_JB_SP */
static struct ThreadContext *st_context;
static unsigned char *st_stack;
static size_t st_stack_size;
static ThreadFunction *st_thread_func;
static void *st_data;
static cs_jmp_buf orig_stack;
/* We can't declare this function static--gcc might want to inline it
in that case, and then the code crashes. I hope this doesn't mean
that the stack is still not getting restored correctly in the above
assembly code. */
void
setup_context_2(void) {
/* Here we are running on the new stack. Copy the key data onto our
new stack. */
ThreadFunction *volatile thread_func = st_thread_func;
void *volatile data = st_data;
if (cs_setjmp(st_context->_jmp_context) == 0) {
/* The _jmp_context is set up and ready to run. Now restore the
original stack and return. We can't simply return from this
function, since it might overwrite some of the stack data on
the way out. */
cs_longjmp(orig_stack);
/* Shouldn't get here. */
abort();
}
/* We come here the first time the thread starts. */
(*thread_func)(data);
/* We shouldn't get here, since we don't expect the thread_func to
return. */
abort();
}
static void
setup_context_1(void) {
/* Save the current stack frame so we can return to it (at the end
of setup_context_2()). */
if (cs_setjmp(orig_stack) == 0) {
/* First, switch to the new stack. Save the current context using
setjmp(). This saves out all of the processor register values,
though it doesn't muck with the stack. */
static cs_jmp_buf temp;
if (cs_setjmp(temp) == 0) {
/* This is the initial return from setjmp. Still the original
stack. */
/* Now we overwrite the stack pointer value in the saved
register context. This doesn't work with all implementations
of setjmp/longjmp. */
/* We give ourselves a small buffer of unused space at the top
of the stack, to allow for the stack frame and such that this
code might be assuming is there. */
(*(void **)&temp[CS_JB_SP]) = (st_stack + st_stack_size - 0x100);
/* And finally, we place ourselves on the new stack by using
longjmp() to reload the modified context. */
cs_longjmp(temp);
/* Shouldn't get here. */
abort();
}
/* This is the second return from setjmp. Now we're on the new
stack. */
setup_context_2();
/* Shouldn't get here. */
abort();
}
/* By now we are back to the original stack. */
}
void
init_thread_context(struct ThreadContext *context,
unsigned char *stack, size_t stack_size,
ThreadFunction *thread_func, void *data) {
/* Copy all of the input parameters to static variables, then begin
the stack-switching process. */
st_context = context;
st_stack = stack;
st_stack_size = stack_size;
st_thread_func = thread_func;
st_data = data;
setup_context_1();
}
void
save_thread_context(struct ThreadContext *context,
ContextFunction *next_context, void *data) {
if (cs_setjmp(context->_jmp_context) != 0) {
/* We have just returned from longjmp. In this case, return from
the function. The stack is still good. */
return;
}
/* We are still in the calling thread. In this case, we cannot
return from the function without damaging the stack. Insted,
call next_context() and trust the caller to call
switch_to_thread_context() in there somewhere. */
(*next_context)(context, data);
/* We shouldn't get here. */
abort();
}
void
switch_to_thread_context(struct ThreadContext *from_context,
struct ThreadContext *to_context) {
cs_longjmp(to_context->_jmp_context);
/* Shouldn't get here. */
abort();
}
struct ThreadContext *
alloc_thread_context() {
struct ThreadContext *context =
(struct ThreadContext *)malloc(sizeof(struct ThreadContext));
memset(context, 0, sizeof(struct ThreadContext));
return context;
}
void
free_thread_context(struct ThreadContext *context) {
free(context);
}

141
panda/src/pipeline/contextSwitch_ucontext_src.c Executable file
View File

@ -0,0 +1,141 @@
/* Filename: contextSwitch_ucontext_src.c
* Created by: drose (15Apr10)
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* PANDA 3D SOFTWARE
* Copyright (c) Carnegie Mellon University. All rights reserved.
*
* All use of this software is subject to the terms of the revised BSD
* license. You should have received a copy of this license along
* with this source code in a file named "LICENSE."
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/* This is the implementation of user-space context switching using
getcontext() / setcontext(). This is the preferred implementation,
if these library functions are available; that's what they are
designed for. */
#ifdef __APPLE__
#include <sys/ucontext.h>
#else
#include <ucontext.h>
#endif
const int needs_stack_prealloc = 1;
struct ThreadContext {
ucontext_t _ucontext;
#ifdef __APPLE__
// Due to a bug in OSX 10.5, the system ucontext_t declaration
// doesn't reserve enough space, and we need to reserve some
// additional space to make room.
#define EXTRA_PADDING_SIZE 4096
char _extra_padding[EXTRA_PADDING_SIZE];
#endif
};
static void
begin_context(ThreadFunction *thread_func, void *data) {
(*thread_func)(data);
}
void
init_thread_context(struct ThreadContext *context,
unsigned char *stack, size_t stack_size,
ThreadFunction *thread_func, void *data) {
if (getcontext(&context->_ucontext) != 0) {
fprintf(stderr, "getcontext failed in init_thread_context!\n");
// Too bad for you.
abort();
}
context->_ucontext.uc_stack.ss_sp = stack;
context->_ucontext.uc_stack.ss_size = stack_size;
context->_ucontext.uc_stack.ss_flags = 0;
context->_ucontext.uc_link = NULL;
makecontext(&context->_ucontext, (void (*)())&begin_context, 2, thread_func, data);
}
void
save_thread_context(struct ThreadContext *context,
ContextFunction *next_context, void *data) {
/* getcontext requires us to use a volatile auto variable to
differentiate between pass 1 (immediate return) and pass 2
(return from setcontext). */
volatile int context_return = 0;
if (getcontext(&context->_ucontext) != 0) {
fprintf(stderr, "getcontext failed!\n");
// Nothing to do here.
abort();
}
if (context_return) {
/* We have just returned from setcontext. In this case, return
from the function. The stack is still good. */
return;
}
context_return = 1;
/* We are still in the calling thread. In this case, we cannot
return from the function without damaging the stack. Insted,
call next_context() and trust the caller to call
switch_to_thread_context() in there somewhere. */
(*next_context)(context, data);
/* We shouldn't get here. */
abort();
}
void
switch_to_thread_context(struct ThreadContext *from_context,
struct ThreadContext *to_context) {
setcontext(&to_context->_ucontext);
/* Shouldn't get here. */
abort();
}
struct ThreadContext *
alloc_thread_context() {
struct ThreadContext *context =
(struct ThreadContext *)malloc(sizeof(struct ThreadContext));
memset(context, 0, sizeof(struct ThreadContext));
#if defined(__APPLE__) && defined(_DEBUG)
{
int p;
// Pre-fill the extra_padding with bytes that we can recognize
// later.
for (p = 0; p < EXTRA_PADDING_SIZE; ++p) {
context->_extra_padding[p] = (p & 0xff);
}
}
#endif // __APPLE__
return context;
}
void
free_thread_context(struct ThreadContext *context) {
#if defined(__APPLE__) && defined(_DEBUG)
{
// Because of the OSX 10.5 bug, we anticipate that the extra_padding
// may have been filled in with junk. Confirm this.
int p = EXTRA_PADDING_SIZE;
while (p > 0) {
--p;
if (context->_extra_padding[p] != (char)(p & 0xff)) {
fprintf(stderr, "Context was mangled at byte %d: %d!\n", p, context->_extra_padding[p]);
break;
}
}
}
#endif // __APPLE__
free(context);
}

153
panda/src/pipeline/contextSwitch_windows_src.c Executable file
View File

@ -0,0 +1,153 @@
/* Filename: contextSwitch_windows_src.c
* Created by: drose (15Apr10)
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* PANDA 3D SOFTWARE
* Copyright (c) Carnegie Mellon University. All rights reserved.
*
* All use of this software is subject to the terms of the revised BSD
* license. You should have received a copy of this license along
* with this source code in a file named "LICENSE."
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/* This is the implementation of user-space context switching using
native Windows threading constructs to manage the different
execution contexts. This isn't strictly user-space, since we use
OS threading constructs, but we use a global lock to ensure that
only one thread at a time is active. Thus, we still don't have to
defend the code against critical sections globally, so we still get
the low-overhead benefit of SIMPLE_THREADS; this is just a simple,
reliable way to manage context switches. */
#include <windows.h>
#include <setjmp.h>
/* The Windows implementation doesn't use the stack pointer. */
const int needs_stack_prealloc = 0;
static struct ThreadContext *current_context = NULL;
struct ThreadContext {
/* Each context is really its own thread. */
HANDLE _thread;
/* This event is in the signaled state when the thread is ready to
roll. */
HANDLE _ready;
// This is set FALSE while the thread is alive, and TRUE if the
// thread is to be terminated when it next wakes up.
int _terminated;
/* These are preloaded with the startup parameters, then cleared to
NULL for subsequent runs. */
ThreadFunction *_thread_func;
void *_data;
/* We use setjmp()/longjmp() to manage the detail of returning from
save_thread_context() when we call switch_to_thread_context(). */
jmp_buf _jmp_context;
};
static DWORD WINAPI
thread_main(LPVOID data) {
struct ThreadContext *context = (struct ThreadContext *)data;
// Wait for the thread to be awoken.
WaitForSingleObject(context->_ready, INFINITE);
if (context->_terminated) {
/* We've been rudely terminated. Exit gracefully. */
ExitThread(1);
}
// Now we can begin.
(*context->_thread_func)(context->_data);
return 0;
}
void
init_thread_context(struct ThreadContext *context,
unsigned char *stack, size_t stack_size,
ThreadFunction *thread_func, void *data) {
context->_thread_func = thread_func;
context->_data = data;
context->_thread = CreateThread(NULL, stack_size,
thread_main, context, 0, NULL);
}
void
save_thread_context(struct ThreadContext *context,
ContextFunction *next_context, void *data) {
/* Save the current context so we can return here when the thread is
awoken. */
if (setjmp(context->_jmp_context) != 0) {
/* We have just returned from longjmp. In this case, return from
the function. */
return;
}
current_context = context;
(*next_context)(context, data);
/* Should not get here. */
assert(FALSE);
abort();
}
void
switch_to_thread_context(struct ThreadContext *from_context,
struct ThreadContext *to_context) {
/* Pause the current thread, and switch to the indicated context.
This function should not return. */
assert(from_context == current_context);
/* Wake up the target thread. */
SetEvent(to_context->_ready);
/* And now put the from thread to sleep until it is again awoken. */
WaitForSingleObject(from_context->_ready, INFINITE);
if (from_context->_terminated) {
/* We've been rudely terminated. Exit gracefully. */
ExitThread(1);
}
/* Now we have been signaled again, and we're ready to resume the
thread. */
longjmp(from_context->_jmp_context, 1);
/* Should not get here. */
assert(FALSE);
abort();
}
struct ThreadContext *
alloc_thread_context() {
struct ThreadContext *context =
(struct ThreadContext *)malloc(sizeof(struct ThreadContext));
memset(context, 0, sizeof(struct ThreadContext));
context->_ready = CreateEvent(NULL, FALSE, FALSE, NULL);
return context;
}
void
free_thread_context(struct ThreadContext *context) {
/* Make sure the thread wakes and exits gracefully. */
context->_terminated = TRUE;
SetEvent(context->_ready);
WaitForSingleObject(context->_thread, INFINITE);
CloseHandle(context->_ready);
if (context->_thread != NULL) {
CloseHandle(context->_thread);
}
free(context);
}

18
panda/src/pipeline/threadSimpleImpl.I
View File

@ -23,6 +23,24 @@ get_current_thread() {
return ThreadSimpleManager::get_global_ptr()->get_current_thread()->_parent_obj;
}
////////////////////////////////////////////////////////////////////
// Function: ThreadSimpleImpl::is_same_system_thread
// Access: Public
// Description: Returns true if we are still running within the same
// OS-level thread that this thread begin in, or false
// if this appears to be running in a different thread.
////////////////////////////////////////////////////////////////////
INLINE bool ThreadSimpleImpl::
is_same_system_thread() const {
#ifdef HAVE_POSIX_THREADS
return pthread_equal(_posix_system_thread_id, pthread_self());
#endif
#ifdef WIN32
return (_win32_system_thread_id == GetCurrentThreadId());
#endif
return true;
}
////////////////////////////////////////////////////////////////////
// Function: ThreadSimpleImpl::bind_thread
// Access: Public, Static

25
panda/src/pipeline/threadSimpleImpl.cxx
View File

@ -51,6 +51,13 @@ ThreadSimpleImpl(Thread *parent_obj) :
// Save this pointer for convenience.
_manager = ThreadSimpleManager::get_global_ptr();
#ifdef HAVE_POSIX_THREADS
_posix_system_thread_id = -1;
#endif
#ifdef WIN32
_win32_system_thread_id = 0;
#endif
}
////////////////////////////////////////////////////////////////////
@ -87,6 +94,13 @@ setup_main_thread() {
_priority = TP_normal;
_priority_weight = _manager->_simple_thread_normal_weight;
#ifdef HAVE_POSIX_THREADS
_posix_system_thread_id = pthread_self();
#endif
#ifdef WIN32
_win32_system_thread_id = GetCurrentThreadId();
#endif
_manager->set_current_thread(this);
}
@ -105,7 +119,9 @@ start(ThreadPriority priority, bool joinable) {
nassertr(_stack == NULL, false);
_stack_size = memory_hook->round_up_to_page_size((size_t)thread_stack_size);
_stack = (unsigned char *)memory_hook->mmap_alloc(_stack_size, true);
if (needs_stack_prealloc) {
_stack = (unsigned char *)memory_hook->mmap_alloc(_stack_size, true);
}
_joinable = joinable;
_status = TS_running;
@ -254,6 +270,13 @@ begin_thread() {
PyThreadState_Swap(_python_state);
#endif // HAVE_PYTHON
#ifdef HAVE_POSIX_THREADS
_posix_system_thread_id = pthread_self();
#endif
#ifdef WIN32
_win32_system_thread_id = GetCurrentThreadId();
#endif
// Here we are executing within the thread. Run the thread_main
// function defined for this thread.
_parent_obj->thread_main();

16
panda/src/pipeline/threadSimpleImpl.h
View File

@ -73,6 +73,8 @@ public:
static void prepare_for_exit();
INLINE static Thread *get_current_thread();
INLINE bool is_same_system_thread() const;
INLINE static void bind_thread(Thread *thread);
INLINE static bool is_threading_supported();
INLINE static bool is_true_threads();
@ -142,6 +144,20 @@ private:
ThreadSimpleManager *_manager;
static ThreadSimpleImpl *volatile _st_this;
// We may not mix-and-match OS threads with Panda's SIMPLE_THREADS.
// If we ever get a Panda context switch request from a different OS
// thread than the thread we think we should be in, that's a serious
// error that may cause major consequences. For this reason, we
// store the OS thread's current thread ID here when the thread is
// constructed, and insist that it never changes during the lifetime
// of the thread.
#ifdef HAVE_POSIX_THREADS
pthread_t _posix_system_thread_id;
#endif
#ifdef WIN32
DWORD _win32_system_thread_id;
#endif
friend class ThreadSimpleManager;
};

12
panda/src/pipeline/threadSimpleManager.I
View File

@ -27,19 +27,13 @@ get_current_thread() {
// Function: ThreadSimpleManager::is_same_system_thread
// Access: Public
// Description: Returns true if we are still running within the same
// OS-level thread that created the ThreadSimpleManager,
// or false if this appears to be running in a different
// OS-level thread we think we should be running in, or
// false if this appears to be running in a different
// thread.
////////////////////////////////////////////////////////////////////
INLINE bool ThreadSimpleManager::
is_same_system_thread() const {
#ifdef HAVE_POSIX_THREADS
return pthread_equal(_posix_system_thread_id, pthread_self());
#endif
#ifdef WIN32
return (_win32_system_thread_id == GetCurrentThreadId());
#endif
return true;
return _current_thread->is_same_system_thread();
}
////////////////////////////////////////////////////////////////////

15
panda/src/pipeline/threadSimpleManager.cxx
View File

@ -78,13 +78,6 @@ ThreadSimpleManager() :
_clock = TrueClock::get_global_ptr();
_waiting_for_exit = NULL;
#ifdef HAVE_POSIX_THREADS
_posix_system_thread_id = pthread_self();
#endif
#ifdef WIN32
_win32_system_thread_id = GetCurrentThreadId();
#endif
// Install these global pointers so very low-level code (code
// defined before the pipeline directory) can yield when necessary.
global_thread_yield = &Thread::force_yield;
@ -542,9 +535,9 @@ init_pointers() {
// of next_context().
////////////////////////////////////////////////////////////////////
void ThreadSimpleManager::
st_choose_next_context(void *data) {
st_choose_next_context(struct ThreadContext *from_context, void *data) {
ThreadSimpleManager *self = (ThreadSimpleManager *)data;
self->choose_next_context();
self->choose_next_context(from_context);
}
////////////////////////////////////////////////////////////////////
@ -554,7 +547,7 @@ st_choose_next_context(void *data) {
// of next_context().
////////////////////////////////////////////////////////////////////
void ThreadSimpleManager::
choose_next_context() {
choose_next_context(struct ThreadContext *from_context) {
double now = get_current_time();
do_timeslice_accounting(_current_thread, now);
@ -696,7 +689,7 @@ choose_next_context() {
<< " blocked, " << _sleeping.size() << " sleeping)\n";
}
switch_to_thread_context(_current_thread->_context);
switch_to_thread_context(from_context, _current_thread->_context);
// Shouldn't get here.
nassertv(false);

18
panda/src/pipeline/threadSimpleManager.h
View File

@ -38,6 +38,7 @@
class Thread;
class ThreadSimpleImpl;
class BlockerSimple;
struct ThreadContext;
////////////////////////////////////////////////////////////////////
// Class : ThreadSimpleManager
@ -87,8 +88,8 @@ private:
typedef pdeque<ThreadSimpleImpl *> FifoThreads;
typedef pvector<ThreadSimpleImpl *> Sleeping;
static void st_choose_next_context(void *data);
void choose_next_context();
static void st_choose_next_context(struct ThreadContext *from_context, void *data);
void choose_next_context(struct ThreadContext *from_context);
void do_timeslice_accounting(ThreadSimpleImpl *thread, double now);
void wake_sleepers(Sleeping &sleepers, double now);
void wake_all_sleepers(Sleeping &sleepers);
@ -159,19 +160,6 @@ private:
TickRecords _tick_records;
unsigned int _total_ticks;
// We may not mix-and-match OS threads with Panda's SIMPLE_THREADS.
// If we ever get a Panda context switch request from a different OS
// thread than the original thread, that's a serious error that may
// cause major consequences. For this reason, we store the OS
// thread's current thread ID here when the manager is constructed,
// and insist that it never changes.
#ifdef HAVE_POSIX_THREADS
pthread_t _posix_system_thread_id;
#endif
#ifdef WIN32
DWORD _win32_system_thread_id;
#endif
static bool _pointers_initialized;
static ThreadSimpleManager *_global_ptr;
};