From 9991b196100873121d054ce95a11faae786138ef Mon Sep 17 00:00:00 2001
From: Geza Lore <gezalore@gmail.com>
Date: Sat, 25 Apr 2020 18:29:27 +0100
Subject: [PATCH] Another attempt at flushing threaded VCD correctly.

---
 include/verilated_vcd_c.cpp | 14 +++++++++-----
 include/verilated_vcd_c.h   |  2 +-
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/include/verilated_vcd_c.cpp b/include/verilated_vcd_c.cpp
index 9f5befff3..f52c80882 100644
--- a/include/verilated_vcd_c.cpp
+++ b/include/verilated_vcd_c.cpp
@@ -274,6 +274,7 @@ void VerilatedVcd::closePrev() {
     // This function is on the flush() call path
     if (!isOpen()) return;
 
+    VerilatedTrace<VerilatedVcd>::flush();
     bufferFlush();
     m_isOpen = false;
     m_filep->close();
@@ -300,13 +301,16 @@ void VerilatedVcd::close() {
         printStr(" $end\n");
     }
     closePrev();
-    // closePrev() already called VerilatedTrace<VerilatedVcd>::flush() via
-    // bufferFlush(), and there were no opportunities to enqueue further
-    // buffers as this close() is running on the main thread the same as dump()
-    // so just shutting down the trace thread will suffice.
+    // closePrev() called VerilatedTrace<VerilatedVcd>::flush(), so we just
+    // need to shut down the tracing thread here.
     VerilatedTrace<VerilatedVcd>::close();
 }
 
+void VerilatedVcd::flush() {
+    VerilatedTrace<VerilatedVcd>::flush();
+    bufferFlush();
+}
+
 void VerilatedVcd::printStr(const char* str) {
     // Not fast...
     while (*str) {
@@ -336,13 +340,13 @@ void VerilatedVcd::bufferResize(vluint64_t minsize) {
 }
 
 void VerilatedVcd::bufferFlush() VL_MT_UNSAFE_ONE {
+    // This function can be called from the trace thread
     // This function is on the flush() call path
     // We add output data to m_writep.
     // When it gets nearly full we dump it using this routine which calls write()
     // This is much faster than using buffered I/O
     m_assertOne.check();
     if (VL_UNLIKELY(!isOpen())) return;
-    VerilatedTrace<VerilatedVcd>::flush();
     char* wp = m_wrBufp;
     while (true) {
         ssize_t remaining = (m_writep - wp);
diff --git a/include/verilated_vcd_c.h b/include/verilated_vcd_c.h
index 0ee8084c8..e9838c15b 100644
--- a/include/verilated_vcd_c.h
+++ b/include/verilated_vcd_c.h
@@ -149,7 +149,7 @@ public:
     /// Close the file
     void close() VL_MT_UNSAFE_ONE;
     /// Flush any remaining data to this file
-    void flush() VL_MT_UNSAFE_ONE { bufferFlush(); }
+    void flush() VL_MT_UNSAFE_ONE;
     /// Is file open?
     bool isOpen() const { return m_isOpen; }