From 24c84e9423db42563de21da76efd4637ca2abcce Mon Sep 17 00:00:00 2001
From: "Nicolas \"Pixel\" Noble" <pixel@nobis-crew.org>
Date: Sun, 10 Aug 2014 22:07:42 -0700
Subject: First pass at the SmartWriter.

---
 includes/SmartWriter.h              |  20 ++++++
 src/SmartWriter.cc                  | 129 ++++++++++++++++++++++++++++++++++++
 win32/project/Balau.vcxproj         |   2 +
 win32/project/Balau.vcxproj.filters |   6 ++
 4 files changed, 157 insertions(+)
 create mode 100644 includes/SmartWriter.h
 create mode 100644 src/SmartWriter.cc

diff --git a/includes/SmartWriter.h b/includes/SmartWriter.h
new file mode 100644
index 0000000..d8baf27
--- /dev/null
+++ b/includes/SmartWriter.h
@@ -0,0 +1,20 @@
+#pragma once
+
+#include <Handle.h>
+
+class SmartWriterTask;
+
+namespace Balau {
+
+class SmartWriter : public Filter {
+  public:
+      SmartWriter(IO<Handle> h) : Filter(h) { AAssert(h->canWrite(), "SmartWriter can't write"); m_name.set("SmartWriter(%s)", h->getName()); }
+    virtual ssize_t write(const void * buf, size_t count) throw (GeneralException) override;
+    virtual const char * getName() override { return m_name.to_charp(); }
+    virtual void close() override;
+  private:
+    SmartWriterTask * m_writerTask = NULL;
+    String m_name;
+};
+
+}
diff --git a/src/SmartWriter.cc b/src/SmartWriter.cc
new file mode 100644
index 0000000..9a32330
--- /dev/null
+++ b/src/SmartWriter.cc
@@ -0,0 +1,129 @@
+#include <StacklessTask.h>
+#include <TaskMan.h>
+#include <SmartWriter.h>
+
+namespace {
+
+struct WriteCell {
+      ~WriteCell() { delete buffer; }
+    const void * buffer = NULL;
+    const uint8_t * ptr;
+    size_t size;
+    bool stop = false;
+    bool close = false;
+};
+
+}
+
+class SmartWriterTask : public Balau::StacklessTask {
+  public:
+      SmartWriterTask(Balau::IO<Balau::Handle> h) : m_h(h) { m_name.set("SmartWriterTask(%s)", h->getName()); }
+    void queueWrite(const void * buf, size_t count) {
+        WriteCell * cell = new WriteCell();
+        uint8_t * copied = (uint8_t *) malloc(count);
+        memcpy(copied, buf, count);
+        cell->buffer = cell->ptr = copied;
+        cell->size = count;
+        m_queue.push(cell);
+    }
+    void stop(bool closeHandle) {
+        WriteCell * cell = new WriteCell();
+        cell->stop = true;
+        cell->close = closeHandle;
+        m_queue.push(cell);
+    }
+    bool gotError() { return m_gotError; }
+  private:
+      virtual ~SmartWriterTask() { empty(); }
+    virtual const char * getName() const override { return m_name.to_charp(); }
+    void empty() {
+        delete m_current;
+        m_current = NULL;
+        while (!m_queue.isEmpty())
+            delete m_queue.pop();
+    }
+    virtual void Do() override {
+        waitFor(m_queue.getEvent());
+        m_queue.getEvent()->resetMaybe();
+
+        bool gotQueue = !m_queue.isEmpty();
+
+        if (gotQueue && !m_current) {
+            m_current = m_queue.pop();
+            gotQueue = !m_queue.isEmpty();
+        }
+
+        if (!gotQueue && !m_current)
+            taskSwitch();
+
+        if (m_current->stop) {
+            if (m_current->close)
+                m_h->close();
+            delete m_current;
+            m_current = NULL;
+            return;
+        }
+
+        ssize_t r = 0;
+        try {
+            r = m_h->write(m_current->ptr, m_current->size);
+        }
+        catch (Balau::EAgain & e) {
+            waitFor(e.getEvent());
+            taskSwitch();
+        }
+
+        m_current->ptr += r;
+        m_current->size -= r;
+
+        if (m_current->size == 0) {
+            delete m_current;
+            m_current = NULL;
+        }
+
+        if (gotQueue || m_current)
+            yield();
+        else
+            taskSwitch();
+    }
+    Balau::IO<Balau::Handle> m_h;
+    Balau::String m_name;
+    std::atomic<bool> m_gotError = false;
+    Balau::TQueue<WriteCell> m_queue;
+    WriteCell * m_current = NULL;
+};
+
+void Balau::SmartWriter::close() {
+    if (m_writerTask) {
+        m_writerTask->stop(!isDetached());
+        m_writerTask = NULL;
+    } else {
+        Filter::close();
+    }
+}
+
+ssize_t Balau::SmartWriter::write(const void * _buf, size_t count) throw (Balau::GeneralException) {
+    const uint8_t * buf = (const uint8_t *) _buf;
+    const ssize_t r = count;
+    while (count) {
+        if (m_writerTask) {
+            if (m_writerTask->gotError())
+                return -1;
+            m_writerTask->queueWrite(buf, count);
+        }
+
+        ssize_t r = 0;
+        try {
+            r = Filter::write(buf, count);
+        }
+        catch (EAgain &) {
+            m_writerTask = TaskMan::registerTask(new SmartWriterTask(getIO()));
+        }
+        if (r < 0)
+            return r;
+        count -= r;
+        buf += r;
+    }
+
+    return r;
+}
diff --git a/win32/project/Balau.vcxproj b/win32/project/Balau.vcxproj
index 44ef4ad..493bb72 100644
--- a/win32/project/Balau.vcxproj
+++ b/win32/project/Balau.vcxproj
@@ -233,6 +233,7 @@
     <ClCompile Include="..\..\src\Printer.cc" />
     <ClCompile Include="..\..\src\Selectable.cc" />
     <ClCompile Include="..\..\src\SimpleMustache.cc" />
+    <ClCompile Include="..\..\src\SmartWriter.cc" />
     <ClCompile Include="..\..\src\Socket.cc" />
     <ClCompile Include="..\..\src\StdIO.cc">
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">true</ExcludedFromBuild>
@@ -294,6 +295,7 @@
     <ClInclude Include="..\..\includes\Printer.h" />
     <ClInclude Include="..\..\includes\Selectable.h" />
     <ClInclude Include="..\..\includes\SimpleMustache.h" />
+    <ClInclude Include="..\..\includes\SmartWriter.h" />
     <ClInclude Include="..\..\includes\Socket.h" />
     <ClInclude Include="..\..\includes\StacklessTask.h" />
     <ClInclude Include="..\..\includes\Task.h" />
diff --git a/win32/project/Balau.vcxproj.filters b/win32/project/Balau.vcxproj.filters
index cd115d4..06a4981 100644
--- a/win32/project/Balau.vcxproj.filters
+++ b/win32/project/Balau.vcxproj.filters
@@ -195,6 +195,9 @@
     <ClCompile Include="..\getopt\getopt.c">
       <Filter>Third Party\getopt</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\src\SmartWriter.cc">
+      <Filter>Source</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="..\..\includes\Async.h">
@@ -365,6 +368,9 @@
     <ClInclude Include="..\getopt\getopt.h">
       <Filter>Third Party\getopt</Filter>
     </ClInclude>
+    <ClInclude Include="..\..\includes\SmartWriter.h">
+      <Filter>Headers</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <None Include="..\..\src\jsoncpp\src\json_internalarray.inl">
-- 
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