Ticket #11801: 0001-Wait-until-there-s-more-space-to-write-in-buffer.patch

mythtv/libs/libmythbase/threadedfilewriter.cpp

@@ -40 +40 @@
     RunEpilog();
 }
 
-const uint ThreadedFileWriter::kMaxBufferSize = 128 * 1024 * 1024;
-const uint ThreadedFileWriter::kMinWriteSize = 64 * 1024;
+const uint ThreadedFileWriter::kMaxBufferSize   = 8 * 1024 * 1024;
+const uint ThreadedFileWriter::kMinWriteSize    = 64 * 1024;
+const uint ThreadedFileWriter::kMaxBlockSize    = 1 * 1024 * 1024;
 
 /** \class ThreadedFileWriter
  *  \brief This class supports the writing of recordings to disk.
@@ -67 +68 @@
     ignore_writes(false),                tfw_min_write_size(kMinWriteSize),
     totalBufferUse(0),
     // threads
-    writeThread(NULL),                   syncThread(NULL)
+    writeThread(NULL),                   syncThread(NULL),
+    m_warned(false)
 {
     filename.detach();
 }
@@ -206 +208 @@
     if (ignore_writes)
         return count;
 
-    if (totalBufferUse + count > kMaxBufferSize)
+    uint written    = 0;
+    uint left       = count;
+
+    while (written < count)
     {
-        LOG(VB_GENERAL, LOG_ERR, LOC +
-                "Maximum buffer size exceeded."
-                "\n\t\t\tfile will be truncated, no further writing "
-                "will be done."
-                "\n\t\t\tThis generally indicates your disk performance "
-                "\n\t\t\tis insufficient to deal with the number of on-going "
-                "\n\t\t\trecordings, or you have a disk failure.");
-        ignore_writes = true;
-        return count;
-    }
+        uint towrite = (left > kMaxBlockSize) ? kMaxBlockSize : left;
 
-    TFWBuffer *buf = NULL;
+        if (totalBufferUse + towrite > kMaxBufferSize)
+        {
+            if (!m_warned)
+            {
+                LOG(VB_GENERAL, LOG_WARNING, LOC +
+                        "Maximum buffer size exceeded."
+                        "\n\t\t\tThis generally indicates your disk performance "
+                        "\n\t\t\tis insufficient or you have a disk failure.");
+                m_warned = true;
+            }
+            // wait until some was written to disk, and try again
+            if (!bufferWasFreed.wait(locker.mutex(), 1000))
+            {
+                LOG(VB_GENERAL, LOG_DEBUG, LOC +
+                    QString("Taking a long time waiting to write.. "
+                            "buffer size %1 (needing %2, %3 to go)")
+                    .arg(totalBufferUse).arg(towrite)
+                    .arg(towrite-(kMaxBufferSize-totalBufferUse)));
+            }
+            continue;
+        }
 
-    if (!writeBuffers.empty() &&
-        (writeBuffers.back()->data.size() + count) < kMinWriteSize)
-    {
-        buf = writeBuffers.back();
-        writeBuffers.pop_back();
-    }
-    else
-    {
-        if (!emptyBuffers.empty())
+        TFWBuffer *buf = NULL;
+
+        if (!writeBuffers.empty() &&
+            (writeBuffers.back()->data.size() + towrite) < kMinWriteSize)
         {
-            buf = emptyBuffers.front();
-            emptyBuffers.pop_front();
-            buf->data.clear();
+            buf = writeBuffers.back();
+            writeBuffers.pop_back();
         }
         else
         {
-            buf = new TFWBuffer();
+            if (!emptyBuffers.empty())
+            {
+                buf = emptyBuffers.front();
+                emptyBuffers.pop_front();
+                buf->data.clear();
+            }
+            else
+            {
+                buf = new TFWBuffer();
+            }
         }
-    }
 
-    totalBufferUse += count;
-    const char *cdata = (const char*) data;
-    buf->data.insert(buf->data.end(), cdata, cdata+count);
-    buf->lastUsed = MythDate::current();
+        totalBufferUse += towrite;
 
-    writeBuffers.push_back(buf);
+        const char *cdata = (const char*) data + written;
+        buf->data.insert(buf->data.end(), cdata, cdata+towrite);
+        buf->lastUsed = MythDate::current();
 
-    if ((writeBuffers.size() > 1) || (buf->data.size() >= kMinWriteSize))
-    {
-        bufferHasData.wakeAll();
+        writeBuffers.push_back(buf);
+
+        if ((writeBuffers.size() > 1) || (buf->data.size() >= kMinWriteSize))
+        {
+            bufferHasData.wakeAll();
+        }
+
+        written += towrite;
+        left    -= towrite;
     }
 
     LOG(VB_FILE, LOG_DEBUG, LOC + QString("Write(*, %1) total %2 cnt %3")
@@ -435 +458 @@
         TFWBuffer *buf = writeBuffers.front();
         writeBuffers.pop_front();
         totalBufferUse -= buf->data.size();
+        bufferWasFreed.wakeAll();
         minWriteTimer.start();
 
         //////////////////////////////////////////

mythtv/libs/libmythbase/threadedfilewriter.h

@@ -95 +95 @@
     QWaitCondition  bufferEmpty;
     QWaitCondition  bufferHasData;
     QWaitCondition  bufferSyncWait;
+    QWaitCondition  bufferWasFreed;
 
     // constants
     static const uint kMaxBufferSize;
     /// Minimum to write to disk in a single write, when not flushing buffer.
     static const uint kMinWriteSize;
+    /// Maximum block size to write at a time
+    static const uint kMaxBlockSize;
+
+    bool m_warned;
 };
 
 #endif