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Commit 601f3c9a authored by Sharvil Nanavati's avatar Sharvil Nanavati Committed by Sharvil Nanavati
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Extend the threading library to back thread with an event queue. 

This change allows arbitrary functions to be called on a given
thread which will clean up much of the dispatch code in bluedroid.
Looking forward, this code will be extended to allow additional objects
and queues to be attached to a thread for more customizable dispatch.

Change-Id: Id6f86435add1a1d13a0f18f3979df68a6ce16663
parent 679ec223

system/osi/include/thread.h

+23 −8
Original line number Diff line number Diff line
@@ -20,16 +20,31 @@ 


#define THREAD_NAME_MAX 16



struct thread_t;

typedef struct thread_t thread_t;

typedef void (*thread_fn)(void *context);



typedef void *(*thread_start_cb) (void *);

// Creates and starts a new thread with the given name. Only THREAD_NAME_MAX

// bytes from |name| will be assigned to the newly-created thread. Returns a

// thread object if the thread was successfully started, NULL otherwise. The

// returned thread object must be freed with |thread_free|. |name| may not

// be NULL.

thread_t *thread_new(const char *name);



// Lifecycle

thread_t *thread_create(const char *name,

                         thread_start_cb start_routine, void *arg);

int thread_join(thread_t *thread, void **retval);

// Frees the given |thread|. If the thread is still running, it is stopped

// and the calling thread will block until |thread| terminates. |thread|

// may be NULL.

void thread_free(thread_t *thread);



// Query

pid_t thread_id(const thread_t *thread);

// Call |func| with the argument |context| on |thread|. This function typically

// does not block unless there are an excessive number of functions posted to

// |thread| that have not been dispatched yet. Neither |thread| nor |func| may

// be NULL. |context| may be NULL.

bool thread_post(thread_t *thread, thread_fn func, void *context);



// Requests |thread| to stop. Only |thread_free| and |thread_name| may be called

// after calling |thread_stop|. This function is guaranteed to not block.

// |thread| may not be NULL.

void thread_stop(thread_t *thread);



// Returns the name of the given |thread|. |thread| may not be NULL.

const char *thread_name(const thread_t *thread);

system/osi/src/thread.c

+126 −51
Original line number Diff line number Diff line
@@ -19,75 +19,59 @@ 
#define LOG_TAG "osi_thread"



#include <assert.h>

#include <errno.h>

#include <pthread.h>

#include <string.h>

#include <sys/prctl.h>

#include <sys/types.h>

#include <utils/Log.h>



#include "fixed_queue.h"

#include "reactor.h"

#include "semaphore.h"

#include "thread.h"



typedef struct thread_t {

struct thread_t {

  pthread_t pthread;

  pid_t tid;

  char name[THREAD_NAME_MAX + 1];

} thread_t;



pid_t thread_id(const thread_t *thread) {

  assert(thread != NULL);

  return thread->tid;

}



const char *thread_name(const thread_t *thread) {

  assert(thread != NULL);

  return thread->name;

}

  reactor_t *reactor;

  fixed_queue_t *work_queue;

};



struct start_arg {

  thread_t *thread;

  semaphore_t *start_sem;

  int error;

  thread_start_cb start_routine;

  void *arg;

};



static void *run_thread(void *start_arg) {

  assert(start_arg != NULL);

typedef struct {

  thread_fn func;

  void *context;

} work_item_t;



  struct start_arg *start = start_arg;

  thread_t *thread = start->thread;

static void *run_thread(void *start_arg);

static void work_queue_read_cb(void *context);



  assert(thread != NULL);

static const size_t WORK_QUEUE_CAPACITY = 128;



  if (prctl(PR_SET_NAME, (unsigned long)thread->name) == -1) {

    ALOGE("%s unable to set thread name: %s", __func__, strerror(errno));

    start->error = errno;

    semaphore_post(start->start_sem);

    return NULL;

  }

  thread->tid = gettid();



  // Cache local values because we are about to let thread_create

  // continue

  thread_start_cb start_routine = start->start_routine;

  void *arg = start->arg;



  semaphore_post(start->start_sem);

  return start_routine(arg);

}



thread_t *thread_create(const char *name,

                        thread_start_cb start_routine, void *arg) {

thread_t *thread_new(const char *name) {

  assert(name != NULL);

  assert(start_routine != NULL);



  // Start is on the stack, but we use a semaphore, so it's safe

  struct start_arg start;

  thread_t *ret;

  ret = calloc(1, sizeof(thread_t));

  thread_t *ret = calloc(1, sizeof(thread_t));

  if (!ret)

    goto error;



  ret->reactor = reactor_new();

  if (!ret->reactor)

    goto error;



  ret->work_queue = fixed_queue_new(WORK_QUEUE_CAPACITY);

  if (!ret->work_queue)

    goto error;



  struct start_arg start;

  start.start_sem = semaphore_new(0);

  if (!start.start_sem)

    goto error;
@@ -95,23 +79,114 @@ thread_t *thread_create(const char *name, 
  strncpy(ret->name, name, THREAD_NAME_MAX);

  start.thread = ret;

  start.error = 0;

  start.start_routine = start_routine;

  start.arg = arg;

  pthread_create(&ret->pthread, NULL, run_thread, &start);

  semaphore_wait(start.start_sem);

  semaphore_free(start.start_sem);

  if (start.error)

    goto error;

  return ret;



error:;

  semaphore_free(start.start_sem);

  if (ret) {

    fixed_queue_free(ret->work_queue, free);

    reactor_free(ret->reactor);

  }

  free(ret);

  return NULL;

}



int thread_join(thread_t *thread, void **retval) {

  int ret = pthread_join(thread->pthread, retval);

  if (!ret)

void thread_free(thread_t *thread) {

  if (!thread)

    return;



  thread_stop(thread);

  pthread_join(thread->pthread, NULL);

  fixed_queue_free(thread->work_queue, free);

  reactor_free(thread->reactor);

  free(thread);

  return ret;

}



bool thread_post(thread_t *thread, thread_fn func, void *context) {

  assert(thread != NULL);

  assert(func != NULL);



  // TODO(sharvil): if the current thread == |thread| and we've run out

  // of queue space, we should abort this operation, otherwise we'll

  // deadlock.



  // Queue item is freed either when the queue itself is destroyed

  // or when the item is removed from the queue for dispatch.

  work_item_t *item = (work_item_t *)malloc(sizeof(work_item_t));

  if (!item) {

    ALOGE("%s unable to allocate memory: %s", __func__, strerror(errno));

    return false;

  }

  item->func = func;

  item->context = context;

  fixed_queue_enqueue(thread->work_queue, item);

  return true;

}



void thread_stop(thread_t *thread) {

  assert(thread != NULL);

  reactor_stop(thread->reactor);

}



const char *thread_name(const thread_t *thread) {

  assert(thread != NULL);

  return thread->name;

}



static void *run_thread(void *start_arg) {

  assert(start_arg != NULL);



  struct start_arg *start = start_arg;

  thread_t *thread = start->thread;



  assert(thread != NULL);



  if (prctl(PR_SET_NAME, (unsigned long)thread->name) == -1) {

    ALOGE("%s unable to set thread name: %s", __func__, strerror(errno));

    start->error = errno;

    semaphore_post(start->start_sem);

    return NULL;

  }

  thread->tid = gettid();



  semaphore_post(start->start_sem);



  reactor_object_t work_queue_object;

  work_queue_object.context = thread->work_queue;

  work_queue_object.fd = fixed_queue_get_dequeue_fd(thread->work_queue);

  work_queue_object.interest = REACTOR_INTEREST_READ;

  work_queue_object.read_ready = work_queue_read_cb;



  reactor_register(thread->reactor, &work_queue_object);

  reactor_start(thread->reactor);



  // Make sure we dispatch all queued work items before exiting the thread.

  // This allows a caller to safely tear down by enqueuing a teardown

  // work item and then joining the thread.

  size_t count = 0;

  work_item_t *item = fixed_queue_try_dequeue(thread->work_queue);

  while (item && count <= WORK_QUEUE_CAPACITY) {

    item->func(item->context);

    free(item);

    item = fixed_queue_try_dequeue(thread->work_queue);

    ++count;

  }



  if (count > WORK_QUEUE_CAPACITY)

    ALOGD("%s growing event queue on shutdown.", __func__);



  return NULL;

}



static void work_queue_read_cb(void *context) {

  assert(context != NULL);



  fixed_queue_t *queue = (fixed_queue_t *)context;

  work_item_t *item = fixed_queue_dequeue(queue);

  item->func(item->context);

  free(item);

}

system/osi/test/thread_test.cpp

+11 −24
Original line number Diff line number Diff line
@@ -5,44 +5,31 @@ extern "C" { 
#include "osi.h"

}



void *start_routine(void *arg)

{

  return arg;

}



TEST(ThreadTest, test_new_simple) {

  thread_t *thread = thread_create("test_thread", &start_routine, NULL);

  thread_t *thread = thread_new("test_thread");

  ASSERT_TRUE(thread != NULL);

  thread_join(thread, NULL);

  thread_free(thread);

}



TEST(ThreadTest, test_join_simple) {

  thread_t *thread = thread_create("test_thread", &start_routine, NULL);

  thread_join(thread, NULL);

TEST(ThreadTest, test_free_simple) {

  thread_t *thread = thread_new("test_thread");

  thread_free(thread);

}



TEST(ThreadTest, test_name) {

  thread_t *thread = thread_create("test_name", &start_routine, NULL);

  thread_t *thread = thread_new("test_name");

  ASSERT_STREQ(thread_name(thread), "test_name");

  thread_join(thread, NULL);

  thread_free(thread);

}



TEST(ThreadTest, test_long_name) {

  thread_t *thread = thread_create("0123456789abcdef", &start_routine, NULL);

  thread_t *thread = thread_new("0123456789abcdef");

  ASSERT_STREQ("0123456789abcdef", thread_name(thread));

  thread_join(thread, NULL);

  thread_free(thread);

}



TEST(ThreadTest, test_very_long_name) {

  thread_t *thread = thread_create("0123456789abcdefg", &start_routine, NULL);

  thread_t *thread = thread_new("0123456789abcdefg");

  ASSERT_STREQ("0123456789abcdef", thread_name(thread));

  thread_join(thread, NULL);

}



TEST(ThreadTest, test_return) {

  int arg = 10;

  void *ret;

  thread_t *thread = thread_create("test", &start_routine, &arg);

  thread_join(thread, &ret);

  ASSERT_EQ(ret, &arg);

  thread_free(thread);

}