reorganize

src/ch07/workq.h

@@ -0,0 +1,59 @@
+/*
+ * workq.h
+ *
+ * This header file defines the interfaces for a "work queue"
+ * manager. A "manager object" is created with several
+ * parameters, including the required size of a work queue
+ * entry, the maximum desired degree of parallelism (number of
+ * threads to service the queue), and the address of an
+ * execution engine routine.
+ *
+ * The application requests a work queue entry from the manager,
+ * fills in the application-specific fields, and returns it to
+ * the queue manager for processing. The manager will create a
+ * new thread to service the queue if all current threads are
+ * busy and the maximum level of parallelism has not yet been
+ * reached.
+ *
+ * The manager will dequeue items and present them to the
+ * processing engine until the queue is empty; at that point,
+ * processing threads will begin to shut down. (They will be
+ * restarted when work appears.)
+ */
+#include <pthread.h>
+
+/*
+ * Structure to keep track of work queue requests.
+ */
+typedef struct workq_ele_tag {
+    struct workq_ele_tag        *next;
+    void                        *data;
+} workq_ele_t;
+
+/*
+ * Structure describing a work queue.
+ */
+typedef struct workq_tag {
+    pthread_mutex_t     mutex;
+    pthread_cond_t      cv;             /* wait for work */
+    pthread_attr_t      attr;           /* create detached threads */
+    workq_ele_t         *first, *last;  /* work queue */
+    int                 valid;          /* set when valid */
+    int                 quit;           /* set when workq should quit */
+    int                 parallelism;    /* number of threads required */
+    int                 counter;        /* current number of threads */
+    int                 idle;           /* number of idle threads */
+    void                (*engine)(void *arg);   /* user engine */
+} workq_t;
+
+#define WORKQ_VALID     0xdec1992
+
+/*
+ * Define work queue functions
+ */
+extern int workq_init (
+    workq_t     *wq,
+    int         threads,                /* maximum threads */
+    void        (*engine)(void *));     /* engine routine */
+extern int workq_destroy (workq_t *wq);
+extern int workq_add (workq_t *wq, void *data);