Changeset 90969 in vbox

Timestamp:

Aug 27, 2021 10:12:22 PM (3 years ago)

Author:

vboxsync

Message:

IPRT/log: Defined the multibuffer flush protocol. bugref:10086

Location:

trunk

Files:

• include/iprt/log.h (modified) (3 diffs)
• src/VBox/Runtime/common/log/log.cpp (modified) (2 diffs)

trunk/include/iprt/log.h

@@ -197 +197 @@
  * Custom buffer flushing function.
  *
- * @retval  true if flushed.
- * @retval  false if flushing pending on other thread and the logger should
- *          switch to the next buffer.  The other thread will call
- *          RTLogFlushDone when finished.
+ * @retval  true if flushed and the buffer can be reused.
+ * @retval  false for switching to the next buffer because an async flush of
+ *          @a pBufDesc is still pending.  The implementation is responsible for
+ *          only returning when the next buffer is ready for reuse, the generic
+ *          logger code has no facility to make sure of this.
+ *
  * @param   pLogger     Pointer to the logger instance which is to be flushed.
  * @param   pBufDesc    The descriptor of the buffer to be flushed.
@@ -288 +290 @@
 
 /** RTLOGBUFFERDESC::u32Magic value. (Avram Noam Chomsky) */
-# define RTLOGBUFFERDESC_MAGIC   UINT32_C(0x19281207)
+#define RTLOGBUFFERDESC_MAGIC   UINT32_C(0x19281207)
 
 /**
@@ -321 +323 @@
 
 /** RTLOGGER::u32Magic value. (John Rogers Searle) */
-#define RTLOGGER_MAGIC      UINT32_C(0x19320731)
+#define RTLOGGER_MAGIC          UINT32_C(0x19320731)
 
 /**

trunk/src/VBox/Runtime/common/log/log.cpp

@@ -3107 +3107 @@
 static void rtlogFlush(PRTLOGGERINTERNAL pLoggerInt, bool fNeedSpace)
 {
-    PRTLOGBUFFERDESC const pBufDesc   = pLoggerInt->pBufDesc;
-    uint32_t               cchToFlush = pBufDesc->offBuf;
-    char * const           pchToFlush = pBufDesc->pchBuf;
-    uint32_t const         cbBuf      = pBufDesc->cbBuf;
+    PRTLOGBUFFERDESC    pBufDesc   = pLoggerInt->pBufDesc;
+    uint32_t            cchToFlush = pBufDesc->offBuf;
+    char * const        pchToFlush = pBufDesc->pchBuf;
+    uint32_t const      cbBuf      = pBufDesc->cbBuf;
     Assert(pBufDesc->u32Magic == RTLOGBUFFERDESC_MAGIC);
 
@@ -3180 +3180 @@
         if (pLoggerInt->pfnFlush)
         {
-            /** @todo implement asynchronous buffer switching protocol. */
-            bool fDone;
+            /*
+             * We have a custom flush callback.  Before calling it we must make
+             * sure the aux descriptor is up to date.  When we get back, we may
+             * need to switch to the next buffer if the current is being flushed
+             * asynchronously.  This of course requires there to be more than one
+             * buffer.  (The custom flush callback is responsible for making sure
+             * the next buffer isn't being flushed before returning.)
+             */
             if (pBufDesc->pAux)
                 pBufDesc->pAux->offBuf = cchToFlush;
-            fDone = pLoggerInt->pfnFlush(&pLoggerInt->Core, pBufDesc);
-            Assert(fDone == true); RT_NOREF(fDone);
-        }
-
-        /* empty the buffer. */
+            if (!pLoggerInt->pfnFlush(&pLoggerInt->Core, pBufDesc))
+            {
+                /* advance to the next buffer */
+                Assert(pLoggerInt->cBufDescs > 1);
+                size_t idxBufDesc = pBufDesc - pLoggerInt->paBufDescs;
+                Assert(idxBufDesc < pLoggerInt->cBufDescs);
+                idxBufDesc = (idxBufDesc + 1) % pLoggerInt->cBufDescs;
+                pLoggerInt->idxBufDesc = (uint8_t)idxBufDesc;
+                pLoggerInt->pBufDesc   = pBufDesc = &pLoggerInt->paBufDescs[idxBufDesc];
+            }
+        }
+
+        /* Empty the buffer. */
         pBufDesc->offBuf = 0;
         if (pBufDesc->pAux)