refactor: wrap existing request queue

runtime/http-parser

@@ -0,0 +1 @@
+Subproject commit 28f3c35c215ffbe0241685901338fad484660454

runtime/include/priority_queue.h

@@ -0,0 +1,32 @@
+#ifndef PRIORITY_QUEUE_H
+#define PRIORITY_QUEUE_H
+
+#include <spinlock/fas.h>
+
+#define MAX 4096
+
+/**
+ * How to get the priority out of the generic element
+ * We assume priority is expressed as an unsigned 64-bit integer (i.e. cycles or
+ * UNIX time in ms). This is used to maintain a read replica of the highest
+ * priority element that can be used to maintain a read replica
+ * @param element
+ * @returns priority (a u64)
+ **/
+typedef unsigned long long int (*priority_queue_get_priority_t)(void *element);
+
+// We assume that priority is expressed in terms of a 64 bit unsigned integral
+struct priority_queue {
+	ck_spinlock_fas_t             lock;
+	unsigned long long int        highest_priority;
+	void *                        items[MAX];
+	int                           first_free;
+	priority_queue_get_priority_t get_priority;
+};
+
+void  priority_queue_initialize(struct priority_queue *self, priority_queue_get_priority_t get_priority);
+int   priority_queue_enqueue(struct priority_queue *self, void *value);
+void *priority_queue_dequeue(struct priority_queue *self);
+int   priority_queue_length(struct priority_queue *self);
+
+#endif /* PRIORITY_QUEUE_H */

runtime/include/runtime.h

@@ -9,8 +9,6 @@
 #include "types.h"
 
 extern int                   runtime_epoll_file_descriptor;
-extern struct deque_sandbox *runtime_global_deque;
-extern pthread_mutex_t       runtime_global_deque_mutex;
 extern __thread uv_loop_t    worker_thread_uvio_handle;
 
 void         alloc_linear_memory(void);

runtime/include/sandbox_request.h

@@ -16,28 +16,6 @@ typedef struct sandbox_request sandbox_request_t;
 
 DEQUE_PROTOTYPE(sandbox, sandbox_request_t *);
 
-/**
- * Pushes a sandbox request to the global deque
- * @param sandbox_request
- **/
-static inline int
-sandbox_request_push_to_dequeue(sandbox_request_t *sandbox_request)
-{
-	int return_code;
-
-// TODO: Running the runtime and listener cores on a single shared core is untested
-// We are unsure if the locking behavior is correct, so there may be deadlocks
-#if NCORES == 1
-	pthread_mutex_lock(&runtime_global_deque_mutex);
-#endif
-	return_code = deque_push_sandbox(runtime_global_deque, &sandbox_request);
-#if NCORES == 1
-	pthread_mutex_unlock(&runtime_global_deque_mutex);
-#endif
-
-	return return_code;
-}
-
 /**
  * Allocates a new Sandbox Request and places it on the Global Deque
  * @param module the module we want to request
@@ -60,57 +38,6 @@ sandbox_request_allocate(struct module *module, char *arguments, int socket_desc
 	sandbox_request->start_time        = start_time;
 
 	debuglog("[%p: %s]\n", sandbox_request, sandbox_request->module->name);
-	sandbox_request_push_to_dequeue(sandbox_request);
-	return sandbox_request;
-}
-
-/**
- * Pops a sandbox request from the global deque
- * @param sandbox_request the pointer which we want to set to the sandbox request
- **/
-static inline int
-sandbox_request_pop_from_dequeue(sandbox_request_t **sandbox_request)
-{
-	int return_code;
-
-// TODO: Running the runtime and listener cores on a single shared core is untested
-// We are unsure if the locking behavior is correct, so there may be deadlocks
-#if NCORES == 1
-	pthread_mutex_lock(&runtime_global_deque_mutex);
-#endif
-	return_code = deque_pop_sandbox(runtime_global_deque, sandbox_request);
-#if NCORES == 1
-	pthread_mutex_unlock(&runtime_global_deque_mutex);
-#endif
-	return return_code;
-}
-
-/**
- * Stealing from the dequeue is a lock-free, cross-core "pop", which removes the element from the end opposite to
- * "pop". Because the producer and consumer (the core stealine the sandbox request) modify different ends,
- * no locks are required, and coordination is achieved by instead retrying on inconsistent indices.
- *
- * Relevant Read: https://www.dre.vanderbilt.edu/~schmidt/PDF/work-stealing-dequeue.pdf
- *
- * TODO: Notice the mutex_lock for NCORES == 1 in both push/pop functions and steal calling 'pop' for NCORES == 1.
- * Ideally you don't call steal for same core consumption but I just made the steal API wrap that logic. Which is
- * perhaps not good. We might just add the #if in the scheduling code which should explicitly call "pop" for single core
- * and add an assert in "steal" function for NCORES == 1.
- *
- * @returns A Sandbox Request or NULL
- **/
-static inline sandbox_request_t *
-sandbox_request_steal_from_dequeue(void)
-{
-	sandbox_request_t *sandbox_request = NULL;
-
-#if NCORES == 1
-	sandbox_request_pop_from_dequeue(&sandbox_request);
-#else
-	int r = deque_steal_sandbox(runtime_global_deque, &sandbox_request);
-	if (r) sandbox_request = NULL;
-#endif
-
 	return sandbox_request;
 }
 

runtime/include/sandbox_request_queue.h

@@ -0,0 +1,10 @@
+#ifndef SFRT_SANDBOX_REQUEST_QUEUE_H
+#define SFRT_SANDBOX_REQUEST_QUEUE_H
+
+#include <sandbox_request.h>
+
+void               sandbox_request_queue_initialize(void);
+int                sandbox_request_queue_add(sandbox_request_t *);
+sandbox_request_t *sandbox_request_queue_remove(void);
+
+#endif /* SFRT_SANDBOX_REQUEST_QUEUE_H */

runtime/jsmn

@@ -0,0 +1 @@
+Subproject commit 85695f3d5903b1cd5b4030efe50db3b4f5f3c928

runtime/src/priority_queue.c

@@ -0,0 +1,207 @@
+#include <assert.h>
+#include <limits.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <priority_queue.h>
+
+/****************************
+ * Private Helper Functions *
+ ****************************/
+
+/**
+ * Adds a value to the end of the binary heap
+ * @param self the priority queue
+ * @param new_item the value we are adding
+ * @return 0 on success. -1 when priority queue is full
+ **/
+static inline int
+priority_queue_append(struct priority_queue *self, void *new_item)
+{
+	assert(self != NULL);
+
+	if (self->first_free >= MAX) return -1;
+
+	self->items[self->first_free] = new_item;
+	self->first_free++;
+	return 0;
+}
+
+/**
+ * Shifts an appended value upwards to restore heap structure property
+ * @param self the priority queue
+ */
+static inline void
+priority_queue_percolate_up(struct priority_queue *self)
+{
+	assert(self != NULL);
+	assert(self->get_priority != NULL);
+
+	for (int i = self->first_free - 1;
+	     i / 2 != 0 && self->get_priority(self->items[i]) < self->get_priority(self->items[i / 2]); i /= 2) {
+		void *temp         = self->items[i / 2];
+		self->items[i / 2] = self->items[i];
+		self->items[i]     = temp;
+		// If percolated to highest priority, update highest priority
+		if (i / 2 == 1) self->highest_priority = self->get_priority(self->items[1]);
+	}
+}
+
+/**
+ * Returns the index of a node's smallest child
+ * @param self the priority queue
+ * @param parent_index
+ * @returns the index of the smallest child
+ */
+static inline int
+priority_queue_find_smallest_child(struct priority_queue *self, int parent_index)
+{
+	assert(self != NULL);
+	assert(parent_index >= 1 && parent_index < self->first_free);
+	assert(self->get_priority != NULL);
+
+	int left_child_index  = 2 * parent_index;
+	int right_child_index = 2 * parent_index + 1;
+	assert(self->items[left_child_index] != NULL);
+
+	// If we don't have a right child or the left child is smaller, return it
+	if (right_child_index == self->first_free) {
+		return left_child_index;
+	} else if (self->get_priority(self->items[left_child_index])
+	           < self->get_priority(self->items[right_child_index])) {
+		return left_child_index;
+	} else {
+		// Otherwise, return the right child
+		return right_child_index;
+	}
+}
+
+/**
+ * Shifts the top of the heap downwards. Used after placing the last value at
+ * the top
+ * @param self the priority queue
+ */
+static inline void
+priority_queue_percolate_down(struct priority_queue *self)
+{
+	assert(self != NULL);
+	assert(self->get_priority != NULL);
+
+	int parent_index     = 1;
+	int left_child_index = 2 * parent_index;
+	while (left_child_index >= 2 && left_child_index < self->first_free) {
+		int smallest_child_index = priority_queue_find_smallest_child(self, parent_index);
+		// Once the parent is equal to or less than its smallest child, break;
+		if (self->get_priority(self->items[parent_index])
+		    <= self->get_priority(self->items[smallest_child_index]))
+			break;
+		// Otherwise, swap and continue down the tree
+		void *temp                        = self->items[smallest_child_index];
+		self->items[smallest_child_index] = self->items[parent_index];
+		self->items[parent_index]         = temp;
+
+		parent_index     = smallest_child_index;
+		left_child_index = 2 * parent_index;
+	}
+}
+
+/*********************
+ * Public API        *
+ *********************/
+
+/**
+ * Initialized the Priority Queue Data structure
+ * @param self the priority_queue to initialize
+ * @param get_priority pointer to a function that returns the priority of an
+ *element
+ **/
+void
+priority_queue_initialize(struct priority_queue *self, priority_queue_get_priority_t get_priority)
+{
+	assert(self != NULL);
+	assert(get_priority != NULL);
+
+	memset(self->items, 0, sizeof(void *) * MAX);
+
+	ck_spinlock_fas_init(&self->lock);
+	self->first_free   = 1;
+	self->get_priority = get_priority;
+
+	// We're assuming a min-heap implementation, so set to larget possible value
+	self->highest_priority = ULONG_MAX;
+}
+
+/**
+ * @param self the priority_queue
+ * @returns the number of elements in the priority queue
+ **/
+int
+priority_queue_length(struct priority_queue *self)
+{
+	assert(self != NULL);
+
+	return self->first_free - 1;
+}
+
+/**
+ * @param self - the priority queue we want to add to
+ * @param value - the value we want to add
+ * @returns 0 on success. -1 on full. -2 on unable to take lock
+ **/
+int
+priority_queue_enqueue(struct priority_queue *self, void *value)
+{
+	assert(self != NULL);
+	int rc;
+
+	if (ck_spinlock_fas_trylock(&self->lock) == false) return -2;
+
+	// Start of Critical Section
+	if (priority_queue_append(self, value) == 0) {
+		if (self->first_free > 2) {
+			priority_queue_percolate_up(self);
+		} else {
+			// If this is the first element we add, update the highest priority
+			self->highest_priority = self->get_priority(value);
+		}
+		rc = 0;
+	} else {
+		// Priority Queue is full
+		rc = -1;
+	}
+	// End of Critical Section
+	ck_spinlock_fas_unlock(&self->lock);
+	return rc;
+}
+
+/**
+ * @param self - the priority queue we want to add to
+ * @returns The head of the priority queue or NULL when empty
+ **/
+void *
+priority_queue_dequeue(struct priority_queue *self)
+{
+	assert(self != NULL);
+	assert(self->get_priority != NULL);
+	// If first_free is 1, we're empty
+	if (self->first_free == 1) return NULL;
+
+	if (ck_spinlock_fas_trylock(&self->lock) == false) return NULL;
+	// Start of Critical Section
+	void *min                         = self->items[1];
+	self->items[1]                    = self->items[self->first_free - 1];
+	self->items[self->first_free - 1] = NULL;
+	self->first_free--;
+	assert(self->first_free == 1 || self->items[self->first_free - 1] != NULL);
+	// Because of 1-based indices, first_free is 2 when there is only one element
+	if (self->first_free > 2) priority_queue_percolate_down(self);
+
+	if (self->first_free > 1) {
+		self->highest_priority = self->get_priority(self->items[1]);
+	} else {
+		self->highest_priority = ULONG_MAX;
+	}
+	ck_spinlock_fas_unlock(&self->lock);
+	// End of Critical Section
+	return min;
+}

runtime/src/runtime.c

@@ -20,6 +20,7 @@
 #include <module.h>
 #include <sandbox.h>
 #include <sandbox_request.h>
+#include <sandbox_request_queue.h>
 #include <software_interrupt.h>
 #include <types.h>
 
@@ -27,8 +28,6 @@
  * Shared Process State    *
  **************************/
 
-struct deque_sandbox *runtime_global_deque;
-pthread_mutex_t       runtime_global_deque_mutex = PTHREAD_MUTEX_INITIALIZER;
 int                  runtime_epoll_file_descriptor;
 http_parser_settings runtime_http_parser_settings;
 
@@ -46,10 +45,7 @@ runtime_initialize(void)
 	assert(runtime_epoll_file_descriptor >= 0);
 
 	// Allocate and Initialize the global deque
-	runtime_global_deque = (struct deque_sandbox *)malloc(sizeof(struct deque_sandbox));
+	sandbox_request_queue_initialize();
-	assert(runtime_global_deque);
-	// Note: Below is a Macro
-	deque_init_sandbox(runtime_global_deque, RUNTIME_MAX_SANDBOX_REQUEST_COUNT);
 
 	// Mask Signals
 	software_interrupt_mask_signal(SIGUSR1);
@@ -106,8 +102,7 @@ listener_thread_main(void *dummy)
 			  sandbox_request_allocate(module, module->name, socket_descriptor,
 			                           (const struct sockaddr *)&client_address, start_time);
 			assert(sandbox_request);
-
+			sandbox_request_queue_add(sandbox_request);
-			// TODO: Refactor sandbox_request_allocate to not add to global request queue and do this here
 		}
 	}
 
@@ -273,7 +268,7 @@ worker_thread_pull_and_process_sandbox_requests(void)
 
 	while (total_sandboxes_pulled < SANDBOX_PULL_BATCH_SIZE) {
 		sandbox_request_t *sandbox_request;
-		if ((sandbox_request = sandbox_request_steal_from_dequeue()) == NULL) break;
+		if ((sandbox_request = sandbox_request_queue_remove()) == NULL) break;
 		// Actually allocate the sandbox for the requests that we've pulled
 		struct sandbox *sandbox = sandbox_allocate(sandbox_request->module, sandbox_request->arguments,
 		                                           sandbox_request->socket_descriptor,

runtime/src/sandbox_request_queue.c

@@ -0,0 +1,137 @@
+#include <sandbox_request_queue.h>
+#include <priority_queue.h>
+
+enum scheduling_policy
+{
+	FIFO,
+	PS
+};
+
+enum scheduling_policy sandbox_request_queue_policy = FIFO;
+
+// FIFO Globals
+struct deque_sandbox *runtime_global_deque;
+pthread_mutex_t       runtime_global_deque_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+// PS Globals
+struct priority_queue sandbox_request_queue_ps;
+
+static inline void
+sandbox_request_queue_fifo_initialize(void)
+{
+	// Allocate and Initialize the global deque
+	runtime_global_deque = (struct deque_sandbox *)malloc(sizeof(struct deque_sandbox));
+	assert(runtime_global_deque);
+	// Note: Below is a Macro
+	deque_init_sandbox(runtime_global_deque, RUNTIME_MAX_SANDBOX_REQUEST_COUNT);
+}
+
+static inline void
+sandbox_request_queue_ps_initialize(void)
+{
+	// TODO
+}
+
+void
+sandbox_request_queue_initialize(void)
+{
+	switch (sandbox_request_queue_policy) {
+	case FIFO:
+		return sandbox_request_queue_fifo_initialize();
+	case PS:
+		return sandbox_request_queue_ps_initialize();
+	}
+}
+
+/**
+ * Pushes a sandbox request to the global deque
+ * @param sandbox_request
+ **/
+static inline int
+sandbox_request_queue_fifo_add(sandbox_request_t *sandbox_request)
+{
+	int return_code;
+
+// TODO: Running the runtime and listener cores on a single shared core is untested
+// We are unsure if the locking behavior is correct, so there may be deadlocks
+#if NCORES == 1
+	pthread_mutex_lock(&runtime_global_deque_mutex);
+#endif
+	return_code = deque_push_sandbox(runtime_global_deque, &sandbox_request);
+#if NCORES == 1
+	pthread_mutex_unlock(&runtime_global_deque_mutex);
+#endif
+
+	return return_code;
+}
+
+static inline int
+sandbox_request_queue_ps_add(sandbox_request_t *sandbox_request)
+{
+	// TODO
+	return 0;
+}
+
+/**
+ * Pushes a sandbox request to the global deque
+ * @param sandbox_request
+ **/
+int
+sandbox_request_queue_add(sandbox_request_t *sandbox_request)
+{
+	switch (sandbox_request_queue_policy) {
+	case FIFO:
+		return sandbox_request_queue_fifo_add(sandbox_request);
+	case PS:
+		return sandbox_request_queue_ps_add(sandbox_request);
+	}
+}
+
+/**
+ * Stealing from the dequeue is a lock-free, cross-core "pop", which removes the element from the end opposite to
+ * "pop". Because the producer and consumer (the core stealine the sandbox request) modify different ends,
+ * no locks are required, and coordination is achieved by instead retrying on inconsistent indices.
+ *
+ * Relevant Read: https://www.dre.vanderbilt.edu/~schmidt/PDF/work-stealing-dequeue.pdf
+ *
+ * TODO: Notice the mutex_lock for NCORES == 1 in both push/pop functions and steal calling 'pop' for NCORES == 1.
+ * Ideally you don't call steal for same core consumption but I just made the steal API wrap that logic. Which is
+ * perhaps not good. We might just add the #if in the scheduling code which should explicitly call "pop" for single core
+ * and add an assert in "steal" function for NCORES == 1.
+ *
+ * @returns A Sandbox Request or NULL
+ **/
+static inline sandbox_request_t *
+sandbox_request_queue_fifo_remove(void)
+{
+	sandbox_request_t *sandbox_request = NULL;
+
+#if NCORES == 1
+	pthread_mutex_lock(&runtime_global_deque_mutex);
+	return_code = deque_pop_sandbox(runtime_global_deque, sandbox_request);
+	pthread_mutex_unlock(&runtime_global_deque_mutex);
+#else
+	int return_code = deque_steal_sandbox(runtime_global_deque, &sandbox_request);
+#endif
+	if (return_code) sandbox_request = NULL;
+	return sandbox_request;
+}
+
+static inline sandbox_request_t *
+sandbox_request_queue_ps_remove(void)
+{
+	sandbox_request_t *sandbox_request = NULL;
+	// TODO
+	return sandbox_request;
+}
+
+sandbox_request_t *
+sandbox_request_queue_remove(void)
+{
+	switch (sandbox_request_queue_policy) {
+	case FIFO:
+		return sandbox_request_queue_fifo_remove();
+	case PS:
+		return sandbox_request_queue_ps_remove();
+	}
+}