Changeset 4e1a2f5 in mainline

Timestamp:

2011-05-16T15:37:37Z (13 years ago)

Author:

Martin Decky <martin@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

bec0219

Parents:

f9061b4

Message:

reimplement klog, use multi-fibril producer/consumer architecture

Location:

uspace

Files:

• app/klog/klog.c (modified) (4 diffs)
• lib/c/Makefile (modified) (1 diff)

uspace/app/klog/klog.c

@@ -44 +44 @@
 #include <io/klog.h>
 #include <sysinfo.h>
+#include <malloc.h>
+#include <fibril_synch.h>
+#include <adt/list.h>
+#include <adt/prodcons.h>
 
 #define NAME       "klog"
 #define LOG_FNAME  "/log/klog"
+
+/* Producer/consumer buffers */
+typedef struct {
+        link_t link;
+        size_t length;
+        wchar_t *data;
+} item_t;
+
+static prodcons_t pc;
 
 /* Pointer to klog area */
@@ -52 +65 @@
 static size_t klog_length;
 
-static FILE *log;
-
-static void interrupt_received(ipc_callid_t callid, ipc_call_t *call)
-{
+/* Notification mutex */
+static FIBRIL_MUTEX_INITIALIZE(mtx);
+
+/** Klog producer
+ *
+ * Copies the contents of a character buffer to local
+ * producer/consumer queue.
+ *
+ * @param length Number of characters to copy.
+ * @param data   Pointer to the kernel klog buffer.
+ *
+ */
+static void producer(size_t length, wchar_t *data)
+{
+        item_t *item = (item_t *) malloc(sizeof(item_t));
+        if (item == NULL)
+                return;
+        
+        size_t sz = sizeof(wchar_t) * length;
+        wchar_t *buf = (wchar_t *) malloc(sz);
+        if (data == NULL) {
+                free(item);
+                return;
+        }
+        
+        memcpy(buf, data, sz);
+        
+        link_initialize(&item->link);
+        item->length = length;
+        item->data = buf;
+        prodcons_produce(&pc, &item->link);
+}
+
+/** Klog consumer
+ *
+ * Waits in an infinite loop for the character data created by
+ * the producer and outputs them to stdout and optionally into
+ * a file.
+ *
+ * @param data Unused.
+ *
+ * @return Always EOK (unreachable).
+ *
+ */
+static int consumer(void *data)
+{
+        FILE *log = fopen(LOG_FNAME, "a");
+        if (log == NULL)
+                printf("%s: Unable to create log file %s (%s)\n", NAME, LOG_FNAME,
+                    str_error(errno));
+        
+        while (true) {
+                link_t *link = prodcons_consume(&pc);
+                item_t *item = list_get_instance(link, item_t, link);
+                
+                for (size_t i = 0; i < item->length; i++)
+                        putchar(item->data[i]);
+                
+                if (log != NULL) {
+                        for (size_t i = 0; i < item->length; i++)
+                                fputc(item->data[i], log);
+                        
+                        fflush(log);
+                        fsync(fileno(log));
+                }
+                
+                free(item->data);
+                free(item);
+        }
+        
+        fclose(log);
+        return EOK;
+}
+
+/** Kernel notification handler
+ *
+ * Receives kernel klog notifications.
+ *
+ * @param callid IPC call ID.
+ * @param call   IPC call structure.
+ *
+ */
+static void notification_received(ipc_callid_t callid, ipc_call_t *call)
+{
+        /*
+         * Make sure we process only a single notification
+         * at any time to limit the chance of the consumer
+         * starving.
+         *
+         * Note: Usually the automatic masking of the klog
+         * notifications on the kernel side does the trick
+         * of limiting the chance of accidentally copying
+         * the same data multiple times. However, due to
+         * the non-blocking architecture of klog notifications,
+         * this possibility cannot be generally avoided.
+         */
+        
+        fibril_mutex_lock(&mtx);
+        
         size_t klog_start = (size_t) IPC_GET_ARG1(*call);
         size_t klog_len = (size_t) IPC_GET_ARG2(*call);
         size_t klog_stored = (size_t) IPC_GET_ARG3(*call);
-        size_t i;
-        
-        for (i = klog_len - klog_stored; i < klog_len; i++) {
-                wchar_t ch = klog[(klog_start + i) % klog_length];
-                
-                putchar(ch);
-                
-                if (log != NULL)
-                        fputc(ch, log);
-        }
-        
-        if (log != NULL) {
-                fflush(log);
-                fsync(fileno(log));
-        }
+        
+        size_t offset = (klog_start + klog_len - klog_stored) % klog_length;
+        
+        /* Copy data from the ring buffer */
+        if (offset + klog_stored >= klog_length) {
+                size_t split = klog_length - offset;
+                
+                producer(split, klog + offset);
+                producer(klog_stored - split, klog);
+        } else
+                producer(klog_stored, klog + offset);
         
         event_unmask(EVENT_KLOG);
+        fibril_mutex_unlock(&mtx);
 }
 
@@ -113 +218 @@
         }
         
-        log = fopen(LOG_FNAME, "a");
-        if (log == NULL)
-                printf("%s: Unable to create log file %s (%s)\n", NAME, LOG_FNAME,
-                    str_error(errno));
-        
-        async_set_interrupt_received(interrupt_received);
+        prodcons_initialize(&pc);
+        async_set_interrupt_received(notification_received);
         rc = event_subscribe(EVENT_KLOG, 0);
         if (rc != EOK) {
-                fclose(log);
                 fprintf(stderr, "%s: Unable to register klog notifications\n",
                     NAME);
@@ -127 +227 @@
         }
         
+        fid_t fid = fibril_create(consumer, NULL);
+        if (!fid) {
+                fprintf(stderr, "%s: Unable to create consumer fibril\n",
+                    NAME);
+                return ENOMEM;
+        }
+        
+        fibril_add_ready(fid);
         event_unmask(EVENT_KLOG);
-        
         klog_update();
+        
+        task_retval(0);
         async_manager();
         

uspace/lib/c/Makefile

@@ -108 +108 @@
         generic/adt/measured_strings.c \
         generic/adt/char_map.c \
+        generic/adt/prodcons.c \
         generic/time.c \
         generic/stdlib.c \