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aioOSX.c
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aioOSX.c
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/*
* I am a new implementation of AIO using kqueue for OSX
*
* This version is supposed to work correctly with pipes and also
* it is supposed to be faster and cheaper.
*
* Sometimes... I think it is too good to be true...
*
*/
#include "pharovm/debug.h"
#include "pharovm/semaphores/platformSemaphore.h"
#include "sqaio.h"
#include "sqMemoryFence.h"
#include "sqaio.h"
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/event.h>
#include <sys/time.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#ifndef NULL
# define NULL 0
#endif
#ifndef true
# define true 1
#endif
#ifndef false
# define false 0
#endif
#define INCOMING_EVENTS_SIZE 50
/*
* This is the struct that I am keeping for the registered FD
*/
typedef struct _AioOSXDescriptor {
int fd;
void* clientData;
aioHandler readHandlerFn;
aioHandler writeHandlerFn;
struct _AioOSXDescriptor* next;
} AioOSXDescriptor;
/*
* I have to keep a list of the registered FDs as the operations are divided in two functions
* I only need to use the aioHandle, but I need information from the aioEnable
*/
AioOSXDescriptor* descriptorList = NULL;
/*
* I can access the elements in the list
*/
AioOSXDescriptor* AioOSXDescriptor_find(int fd);
void AioOSXDescriptor_remove(int fd);
/*
* This is kqueue used in the poll of the events.
*/
int kqueueDescriptor;
/*
* These functions are used to notify the heartbeat if we are entering and leaving a long pause.
* Maybe the heartbeat want to stop if we are in a long pause.
*/
void heartbeat_poll_enter(long microSeconds);
void heartbeat_poll_exit(long microSeconds);
static int aio_handle_events(struct kevent* changes, int numberOfChanges, long microSecondsTimeout);
/*
* This is important, the AIO poll should only do a long pause if there is no pending signals for semaphores.
* Check ExternalSemaphores to understand this function.
*/
int isPendingSemaphores();
/*
* The access to the pendingInterruption variable is done through the use of a mutex
*/
Semaphore * interruptFIFOMutex;
volatile int pendingInterruption = 0;
volatile int isPooling = 0;
#define INTERRUPT_EVENT_ID 0
/*
* I initialize the AIO infrastructure
*/
EXPORT(void)
aioInit(void){
struct kevent userEvent;
if((kqueueDescriptor = kqueue()) < 0) {
logErrorFromErrno("kqueue");
}
interruptFIFOMutex = platform_semaphore_new(1);
EV_SET(&userEvent, INTERRUPT_EVENT_ID, EVFILT_USER, EV_ADD | EV_CLEAR, 0, 0, NULL);
kevent(kqueueDescriptor, &userEvent, 1, NULL, 0, NULL);
}
/*
* I process the changes and then process the events calling the handlers
* if there is one.
*
* I return if messages has been processed.
* Also I clean up the pipe if there are notifications.
*/
static int
aio_handle_events(struct kevent* changes, int numberOfChanges, long microSecondsTimeout){
struct kevent incomingEvents[INCOMING_EVENTS_SIZE];
int keventReturn;
struct timespec timeout;
//I notify the heartbeat of a pause
heartbeat_poll_enter(microSecondsTimeout);
sqLowLevelMFence();
isPooling = 1;
timeout.tv_nsec = (microSecondsTimeout % 1000000) * 1000;
timeout.tv_sec = microSecondsTimeout / 1000000;
keventReturn = kevent(kqueueDescriptor, changes, numberOfChanges, incomingEvents, INCOMING_EVENTS_SIZE, &timeout);
sqLowLevelMFence();
isPooling = 0;
interruptFIFOMutex->wait(interruptFIFOMutex);
pendingInterruption = false;
interruptFIFOMutex->signal(interruptFIFOMutex);
//I notify the heartbeat of the end of the pause
heartbeat_poll_exit(microSecondsTimeout);
if(keventReturn == -1){
if(errno != EINTR){
logErrorFromErrno("kevent");
}
return 0;
}
if(keventReturn == 0){
return 0;
}
for(int index = 0; index < keventReturn; index++){
//First I check if the event is an error in the registration
if((incomingEvents[index].flags & EV_ERROR) && (incomingEvents[index].flags & EV_ADD)){
int previousErrno = errno;
logError("Error registering FD: %d", (int) incomingEvents[index].ident);
errno = incomingEvents[index].data;
logErrorFromErrno("Registering event");
errno = previousErrno;
}else{
//If the event is not of the signal pipe I process them
if(incomingEvents[index].filter != EVFILT_USER){
//If not is a regular registered FD
AioOSXDescriptor *descriptor = (AioOSXDescriptor*)incomingEvents[index].udata;
if((incomingEvents[index].filter & EVFILT_READ) == EVFILT_READ){
if(descriptor->readHandlerFn)
descriptor->readHandlerFn(incomingEvents[index].ident, descriptor->clientData, AIO_R);
}
if((incomingEvents[index].filter & EVFILT_WRITE) == EVFILT_WRITE){
if(descriptor->writeHandlerFn)
descriptor->writeHandlerFn(incomingEvents[index].ident, descriptor->clientData, AIO_W);
}
}
}
}
return 1;
}
/*
* There is no implementation of the shutdown.
*/
EXPORT(void)
aioFini(void){
}
/*
* This is the entry point to the aioPoll
* The parameter is the maximum time the poll will stop.
* The pause can be smaller if there are pending interruptions or pending signals to semaphores
* from external semaphores.
* Also if there is IO operations it will return ASAP.
*/
EXPORT(long)
aioPoll(long microSeconds){
long timeout;
interruptFIFOMutex->wait(interruptFIFOMutex);
if(pendingInterruption || isPendingSemaphores()){
timeout = 0;
}else{
timeout = microSeconds;
}
if(pendingInterruption){
pendingInterruption = false;
}
interruptFIFOMutex->signal(interruptFIFOMutex);
return aio_handle_events(NULL, 0, timeout);
}
/*
* With this is is possible to interrupt a long AIO poll.
* The external semaphores uses this function to interrupt the poll loop.
*/
EXPORT(void)
aioInterruptPoll(){
int n;
struct kevent userEvent;
sqLowLevelMFence();
if(isPooling){
EV_SET(&userEvent, INTERRUPT_EVENT_ID, EVFILT_USER, 0, NOTE_TRIGGER, 0, NULL);
kevent(kqueueDescriptor, &userEvent, 1, NULL, 0, NULL);
}
interruptFIFOMutex->wait(interruptFIFOMutex);
pendingInterruption = true;
interruptFIFOMutex->signal(interruptFIFOMutex);
}
/*
* I am part of the API of AIO
* I enable the FD to use AIO.
* The possible flags are here: AIO_EXT if the FD is external (and we should not change its properties).
* This function should be call to each FD to use.
*/
EXPORT(void)
aioEnable(int fd, void *clientData, int flags){
AioOSXDescriptor * descriptor;
descriptor = AioOSXDescriptor_find(fd);
if(descriptor == NULL){
descriptor = malloc(sizeof(AioOSXDescriptor));
descriptor->readHandlerFn = NULL;
descriptor->writeHandlerFn = NULL;
descriptor->next = descriptorList;
descriptorList = descriptor;
}
descriptor->fd = fd;
descriptor->clientData = clientData;
if ((flags & AIO_EXT) != AIO_EXT) {
/*
* enable non-blocking asynchronous i/o and delivery of SIGIO
* to the active process
*/
int arg;
if (fcntl(fd, F_SETOWN, getpid()) < 0)
logErrorFromErrno("fcntl(F_SETOWN, getpid())");
if ((arg = fcntl(fd, F_GETFL, 0)) < 0)
logErrorFromErrno("fcntl(F_GETFL)");
if (fcntl(fd, F_SETFL, arg | O_NONBLOCK | O_ASYNC) < 0)
logErrorFromErrno("fcntl(F_SETFL, O_ASYNC)");
}
}
/*
* This function is part of the API
* This is used to suspend the receive of events.
* The mask parameter says which handlers to suspend, it can be any combinatio of
*
* - AIO_R
* - AIO_W
*/
EXPORT(void)
aioSuspend(int fd, int mask){
int cant = 0;
int nextIndex = 0;
struct kevent newEvents[2];
AioOSXDescriptor *descriptor = AioOSXDescriptor_find(fd);
if(descriptor == NULL){
logWarn("Suspending a FD that is not present: %d - IGNORING", fd);
return;
}
if((mask & AIO_R) == AIO_R){
descriptor->readHandlerFn = NULL;
EV_SET(&newEvents[nextIndex], fd, EVFILT_READ, EV_DELETE, 0, 0, descriptor);
nextIndex++;
cant++;
}
if((mask & AIO_W) == AIO_W){
descriptor->writeHandlerFn = NULL;
EV_SET(&newEvents[nextIndex], fd, EVFILT_WRITE, EV_DELETE, 0, 0, descriptor);
nextIndex++;
cant++;
}
aio_handle_events(newEvents, cant, 0);
}
/*
* I disable all the events of a given FD and I forget about it!
*/
EXPORT(void)
aioDisable(int fd){
aioSuspend(fd, AIO_RWX);
AioOSXDescriptor_remove(fd);
}
/*
* This function is part of the API
* This is used to enable the receive of events.
* The mask parameter says which handlers to receive with this handle, it can be any combination of:
*
* - AIO_R
* - AIO_W
*
* Once the event arrives and the handle is notified, it will be disabled.
* If the same event is desired again, it should be re-register.
*/
EXPORT(void)
aioHandle(int fd, aioHandler handlerFn, int mask){
struct kevent newEvents[2];
AioOSXDescriptor *descriptor = AioOSXDescriptor_find(fd);
if(descriptor == NULL){
logWarn("Enabling a FD that is not present: %d - IGNORING", fd);
return;
}
int hasRead = (mask & AIO_R) == AIO_R;
int hasWrite = (mask & AIO_W) == AIO_W;
descriptor->readHandlerFn = hasRead ? handlerFn : NULL;
EV_SET(&newEvents[0], fd, EVFILT_READ, hasRead?(EV_ADD | EV_ONESHOT):EV_DELETE, 0, 0, descriptor);
descriptor->writeHandlerFn = hasWrite ? handlerFn : NULL;
EV_SET(&newEvents[1], fd, EVFILT_WRITE, hasWrite?(EV_ADD | EV_ONESHOT):EV_DELETE, 0, 0, descriptor);
aio_handle_events(newEvents, 2, 0);
}
AioOSXDescriptor* AioOSXDescriptor_find(int fd){
AioOSXDescriptor* found;
found = descriptorList;
while(found != NULL){
if(found->fd == fd)
return found;
found = found->next;
}
return NULL;
}
void AioOSXDescriptor_remove(int fd){
AioOSXDescriptor* found;
AioOSXDescriptor* prev = NULL;
found = descriptorList;
while(found != NULL){
if(found->fd == fd){
if(descriptorList == found){
descriptorList = found->next;
}else{
prev->next = found->next;
}
free(found);
return;
}
prev = found;
found = found->next;
}
}