Clean concurrency utilities

kernel/include/conc/condition_variable.hpp

@@ -5,8 +5,8 @@
 //  http://www.opensource.org/licenses/MIT)
 //=======================================================================
 
-#ifndef SLEEP_QUEUE_H
-#define SLEEP_QUEUE_H
+#ifndef CONDITION_VARIABLE_H
+#define CONDITION_VARIABLE_H
 
 #include <circular_buffer.hpp>
 #include <lock_guard.hpp>
@@ -18,12 +18,7 @@
 /*!
  * \brief A simple sleep queue
  */
-struct sleep_queue {
-private:
-    mutable spinlock lock;
-    circular_buffer<scheduler::pid_t, 16> queue;
-
-public:
+struct condition_variable {
     /*!
      * \brief Test if the sleep queue is empty
      */
@@ -58,6 +53,10 @@ public:
      * \return true if the thread was woken up, false if the timeout is passed
      */
     bool sleep(size_t ms);
+
+private:
+    mutable spinlock lock;                       ///< The spin lock used for protecting the queue
+    circular_buffer<scheduler::pid_t, 16> queue; ///< The queue of waiting threads
 };
 
 #endif

kernel/include/conc/int_lock.hpp

@@ -12,32 +12,51 @@
 
 #include "arch.hpp"
 
+/*!
+ * \brief An interrupt lock. This lock disable preemption on acquire.
+ */
 struct int_lock {
-private:
-    size_t rflags;
-
-public:
+    /*!
+     * \brief Acquire the lock. This will disable preemption.
+     */
     void acquire(){
         arch::disable_hwint(rflags);
     }
 
+    /*!
+     * \brief Release the lock. This will enable preemption.
+     */
     void release(){
         arch::enable_hwint(rflags);
     }
+
+private:
+    size_t rflags; ///< The CPU flags
 };
 
+/*!
+ * \brief A direct interrupt lock (RAII).
+ *
+ * This is the equivalent of a std::lock_guard<int_lock> but does not need to
+ * store a lock.
+ */
 struct direct_int_lock {
-private:
-    int_lock lock;
-
-public:
+    /*!
+     * \brief Construct a new direct_int_lock and acquire the lock.
+     */
     direct_int_lock(){
         lock.acquire();
     }
 
+    /*!
+     * \brief Destruct a direct_int_lock and release the lock.
+     */
     ~direct_int_lock(){
         lock.release();
     }
+
+private:
+    int_lock lock; ///< The interrupt lock
 };
 
 #endif

kernel/include/conc/mutex.hpp

@@ -16,72 +16,66 @@
 #include "scheduler.hpp"
 #include "logging.hpp"
 
-template<bool Debug = false>
+/*!
+ * \brief A mutex implementation.
+ *
+ * Once the lock is acquired, the critical section is only accessible by the
+ * thread who acquired the mutex.
+ */
 struct mutex {
-private:
-    mutable spinlock lock;
-    volatile size_t value;
-    circular_buffer<scheduler::pid_t, 16> queue;
-    const char* name;
-
-public:
+    /*!
+     * \brief Initialize the mutex (either to 1 or 0)
+     * \param v The intial value of the mutex
+     */
     void init(size_t v = 1){
-        value = v;
-
-        if(Debug){
-            name = "";
+        if(v > 1){
+            value = 1;
+        } else {
+            value = v;
         }
     }
 
-    void set_name(const char* name){
-        this->name = name;
-    }
-
+    /*!
+     * \brief Acquire the lock
+     */
     void acquire(){
         lock.acquire();
 
         if(value > 0){
             value = 0;
 
-            if(Debug){
-                logging::logf(logging::log_level::TRACE, "%s(mutex): directly acquired (process %d)\n", name, scheduler::get_pid());
-            }
-
             lock.release();
         } else {
             auto pid = scheduler::get_pid();
             queue.push(pid);
 
-            if(Debug){
-                logging::logf(logging::log_level::TRACE, "%s(mutex): wait %d\n", name, pid);
-            }
-
             scheduler::block_process_light(pid);
             lock.release();
             scheduler::reschedule();
         }
     }
 
+    /*!
+     * \brief Acquire the lock
+     */
     void release(){
         std::lock_guard<spinlock> l(lock);
 
         if(queue.empty()){
             value = 1;
-            if(Debug){
-                logging::logf(logging::log_level::TRACE, "%s(mutex): direct release (process %d)\n", name, scheduler::get_pid());
-            }
         } else {
             auto pid = queue.pop();
             scheduler::unblock_process(pid);
 
-            if(Debug){
-                logging::logf(logging::log_level::TRACE, "%s(mutex): wake %d\n", name, pid);
-            }
-
             //No need to increment value, the process won't
             //decrement it
         }
     }
+
+private:
+    mutable spinlock lock;                       ///< The spin protecting the value
+    volatile size_t value;                       ///< The value of the mutex
+    circular_buffer<scheduler::pid_t, 16> queue; ///< The sleep queue
 };
 
 #endif

kernel/include/conc/semaphore.hpp

@@ -14,17 +14,26 @@
 #include "spinlock.hpp"
 #include "scheduler.hpp"
 
+/*!
+ * \brief A semaphore implementation.
+ *
+ * The critical section can be open to several processes.
+ */
 struct semaphore {
-private:
-    mutable spinlock lock;
-    volatile size_t value;
-    circular_buffer<scheduler::pid_t, 16> queue;
-
-public:
+    /*!
+     * \brief Initialize the semaphore
+     * \param v The intial value of the semaphore
+     */
     void init(size_t v){
         value = v;
     }
 
+    /*!
+     * \brief Acquire the lock.
+     *
+     * This will effectively decrease the current counter by 1 once the critical
+     * section is entered.
+     */
     void acquire(){
         lock.acquire();
 
@@ -41,6 +50,12 @@ public:
         }
     }
 
+    /*!
+     * \brief Release the lock.
+     *
+     * This will effectively increase the current counter by 1 once the critical
+     * section is left.
+     */
     void release(){
         std::lock_guard<spinlock> l(lock);
 
@@ -56,23 +71,34 @@ public:
         }
     }
 
-    void release(size_t v){
+    /*!
+     * \brief Release the lock several times.
+     *
+     * This will effectively increase the current counter by n once the critical
+     * section is left.
+     */
+    void release(size_t n){
         std::lock_guard<spinlock> l(lock);
 
         if(queue.empty()){
-            value += v;
+            value += n;
         } else {
-            while(v && !queue.empty()){
+            while(n && !queue.empty()){
                 auto pid = queue.pop();
                 scheduler::unblock_process(pid);
-                --v;
+                --n;
             }
 
-            if(v){
-                value += v;
+            if(n){
+                value += n;
             }
         }
     }
+
+private:
+    mutable spinlock lock;                       ///< The spin lock protecting the counter
+    volatile size_t value;                       ///< The value of the counter
+    circular_buffer<scheduler::pid_t, 16> queue; ///< The sleep queue
 };
 
 #endif

kernel/include/conc/spinlock.hpp

@@ -8,21 +8,33 @@
 #ifndef SPINLOCK_H
 #define SPINLOCK_H
 
+/*!
+ * \brief Implementation of a spinlock
+ *
+ * A spinlock simply waits in a loop until the lock is available.
+ */
 struct spinlock {
-private:
-    volatile size_t lock = 0;
-
-public:
+    /*!
+     * \brief Acquire the lock.
+     *
+     * This will wait indefinitely.
+     */
     void acquire(){
         while(!__sync_bool_compare_and_swap(&lock, 0, 1));
         __sync_synchronize();
         //TODO The last synchronize is probably not necessary
     }
 
+    /*!
+     * \brief Release the lock
+     */
     void release(){
         __sync_synchronize();
         lock = 0;
     }
+
+private:
+    volatile size_t lock = 0; ///< The value of the lock
 };
 
 #endif

kernel/include/net/network.hpp

@@ -37,7 +37,7 @@ struct interface_descriptor {
     network::ip::address ip_address; ///< The interface IP address
     network::ip::address gateway;    ///< The interface IP gateway
 
-    mutable mutex<> tx_lock; //To synchronize the queue
+    mutable mutex tx_lock; //To synchronize the queue
     mutable semaphore tx_sem;
     mutable semaphore rx_sem;
 
@@ -50,7 +50,7 @@ struct interface_descriptor {
     void (*hw_send)(interface_descriptor&, ethernet::packet& p);
 
     void send(ethernet::packet& p){
-        std::lock_guard<mutex<>> l(tx_lock);
+        std::lock_guard<mutex> l(tx_lock);
         tx_queue.push(p);
         tx_sem.release();
     }

kernel/include/net/socket.hpp

@@ -15,7 +15,7 @@
 
 #include "tlib/net_constants.hpp"
 
-#include "conc/sleep_queue.hpp"
+#include "conc/condition_variable.hpp"
 
 #include "net/ethernet_packet.hpp"
 
@@ -41,7 +41,7 @@ struct socket {
     std::vector<network::ethernet::packet> packets;
 
     circular_buffer<network::ethernet::packet, 32> listen_packets;
-    sleep_queue listen_queue;
+    condition_variable listen_queue;
 
     socket(){}
     socket(size_t id, socket_domain domain, socket_type type, socket_protocol protocol, size_t next_fd, bool listen)

kernel/include/terminal.hpp

@@ -13,7 +13,7 @@
 
 #include <tlib/keycode.hpp>
 
-#include "conc/sleep_queue.hpp"
+#include "conc/condition_variable.hpp"
 
 namespace stdio {
 
@@ -35,7 +35,7 @@ struct virtual_terminal {
     circular_buffer<char, 2 * INPUT_BUFFER_SIZE> canonical_buffer;
     circular_buffer<size_t, 3 * INPUT_BUFFER_SIZE> raw_buffer;
 
-    sleep_queue input_queue;
+    condition_variable input_queue;
 
     void print(char c);
 

kernel/src/conc/condition_variable.cpp

@@ -5,25 +5,25 @@
 //  http://www.opensource.org/licenses/MIT)
 //=======================================================================
 
-#include "conc/sleep_queue.hpp"
+#include "conc/condition_variable.hpp"
 
 #include "scheduler.hpp"
 #include "logging.hpp"
 #include "assert.hpp"
 
-bool sleep_queue::empty() const {
+bool condition_variable::empty() const {
     std::lock_guard<spinlock> l(lock);
 
     return queue.empty();
 }
 
-scheduler::pid_t sleep_queue::top_process() const {
+scheduler::pid_t condition_variable::top_process() const {
     std::lock_guard<spinlock> l(lock);
 
     return queue.top();
 }
 
-scheduler::pid_t sleep_queue::wake_up() {
+scheduler::pid_t condition_variable::wake_up() {
     std::lock_guard<spinlock> l(lock);
 
     while (!queue.empty()) {
@@ -34,7 +34,7 @@ scheduler::pid_t sleep_queue::wake_up() {
         queue.pop();
 
         if (pid != scheduler::INVALID_PID) {
-            logging::logf(logging::log_level::TRACE, "sleep_queue: wake %d\n", pid);
+            logging::logf(logging::log_level::TRACE, "condition_variable: wake %d\n", pid);
 
             // Indicate to the scheduler that this process will be able to run
             // We use a hint here because it is possible that the thread was
@@ -48,7 +48,7 @@ scheduler::pid_t sleep_queue::wake_up() {
     return scheduler::INVALID_PID;
 }
 
-void sleep_queue::wake_up_all() {
+void condition_variable::wake_up_all() {
     std::lock_guard<spinlock> l(lock);
 
     while (!queue.empty()) {
@@ -59,7 +59,7 @@ void sleep_queue::wake_up_all() {
         queue.pop();
 
         if (pid != scheduler::INVALID_PID) {
-            logging::logf(logging::log_level::TRACE, "sleep_queue: wake(all) %d\n", pid);
+            logging::logf(logging::log_level::TRACE, "condition_variable: wake(all) %d\n", pid);
 
             // Indicate to the scheduler that this process will be able to run
             // We use a hint here because it is possible that the thread was
@@ -69,18 +69,18 @@ void sleep_queue::wake_up_all() {
     }
 }
 
-void sleep_queue::sleep() {
+void condition_variable::sleep() {
     lock.acquire();
 
     //Get the current process information
     auto pid = scheduler::get_pid();
 
-    logging::logf(logging::log_level::TRACE, "sleep_queue: wait %d\n", pid);
+    logging::logf(logging::log_level::TRACE, "condition_variable: wait %d\n", pid);
 
     //Enqueue the process in the sleep queue
     queue.push(pid);
 
-    thor_assert(!queue.full(), "The sleep_queue queue is full!");
+    thor_assert(!queue.full(), "The condition_variable queue is full!");
 
     //This process will sleep
     scheduler::block_process_light(pid);
@@ -90,7 +90,7 @@ void sleep_queue::sleep() {
     scheduler::reschedule();
 }
 
-bool sleep_queue::sleep(size_t ms) {
+bool condition_variable::sleep(size_t ms) {
     if (!ms) {
         return false;
     }
@@ -100,12 +100,12 @@ bool sleep_queue::sleep(size_t ms) {
     //Get the current process information
     auto pid = scheduler::get_pid();
 
-    logging::logf(logging::log_level::TRACE, "sleep_queue: %u wait with timeout %u\n", pid, ms);
+    logging::logf(logging::log_level::TRACE, "condition_variable: %u wait with timeout %u\n", pid, ms);
 
     //Enqueue the process in the sleep queue
     queue.push(pid);
 
-    thor_assert(!queue.full(), "The sleep_queue queue is full!");
+    thor_assert(!queue.full(), "The condition_variable queue is full!");
 
     //This process will sleep
     scheduler::block_process_timeout_light(pid, ms);

kernel/src/drivers/ata.cpp

@@ -28,10 +28,10 @@ static constexpr const size_t BLOCK_SIZE = 512;
 
 ata::drive_descriptor* drives;
 
-mutex<> ata_lock;
+mutex ata_lock;
 
-mutex<> primary_lock;
-mutex<> secondary_lock;
+mutex primary_lock;
+mutex secondary_lock;
 
 block_cache cache;
 
@@ -350,10 +350,6 @@ void ata::detect_disks(){
     primary_lock.init(0);
     secondary_lock.init(0);
 
-    ata_lock.set_name("ata_lock");
-    primary_lock.set_name("ata_primary_lock");
-    secondary_lock.set_name("ata_secondary_lock");
-
     // Init the cache with 256 blocks
     cache.init(BLOCK_SIZE, 256);
 

kernel/src/net/arp_layer.cpp

@@ -14,14 +14,14 @@
 #include "net/arp_cache.hpp"
 #include "net/ip_layer.hpp"
 
-#include "conc/sleep_queue.hpp"
+#include "conc/condition_variable.hpp"
 
 #include "logging.hpp"
 #include "kernel_utils.hpp"
 
 namespace {
 
-sleep_queue wait_queue;
+condition_variable wait_queue;
 
 } //end of anonymous namespace
 

kernel/src/net/tcp_layer.cpp

@@ -9,7 +9,7 @@
 #include <atomic.hpp>
 #include <list.hpp>
 
-#include "conc/sleep_queue.hpp"
+#include "conc/condition_variable.hpp"
 
 #include "net/tcp_layer.hpp"
 #include "net/dns_layer.hpp"
@@ -41,7 +41,7 @@ struct tcp_connection {
     size_t target_port;
 
     std::atomic<bool> listening;
-    sleep_queue queue;
+    condition_variable queue;
     circular_buffer<network::ethernet::packet, 8> packets;
 
     tcp_connection(size_t source_port, size_t target_port)