Stop abusing errno

[folly.git] / folly / io / async / AsyncSocket.h

diff --git a/folly/io/async/AsyncSocket.h b/folly/io/async/AsyncSocket.h
index ba706747c57a8a46e32950eebdb98aefbe7af20c..37fdf08e89318c8703e176f061e57326bde9c4b6 100644 (file)
--- a/folly/io/async/AsyncSocket.h
+++ b/folly/io/async/AsyncSocket.h
@@ -16,16 +16,17 @@
 
 #pragma once
 
-#include <sys/types.h>
-#include <sys/socket.h>
+#include <folly/Optional.h>
 #include <folly/SocketAddress.h>
-#include <folly/io/ShutdownSocketSet.h>
 #include <folly/io/IOBuf.h>
-#include <folly/io/async/AsyncTimeout.h>
+#include <folly/io/ShutdownSocketSet.h>
 #include <folly/io/async/AsyncSocketException.h>
+#include <folly/io/async/AsyncTimeout.h>
 #include <folly/io/async/AsyncTransport.h>
-#include <folly/io/async/EventHandler.h>
 #include <folly/io/async/DelayedDestruction.h>
+#include <folly/io/async/EventHandler.h>
+#include <sys/socket.h>
+#include <sys/types.h>
 
 #include <chrono>
 #include <memory>
@@ -517,6 +518,41 @@ class AsyncSocket : virtual public AsyncTransportWrapper {
 
   void setBufferCallback(BufferCallback* cb);
 
+  /**
+   * writeReturn is the total number of bytes written, or WRITE_ERROR on error.
+   * If no data has been written, 0 is returned.
+   * exception is a more specific exception that cause a write error.
+   * Not all writes have exceptions associated with them thus writeReturn
+   * should be checked to determine whether the operation resulted in an error.
+   */
+  struct WriteResult {
+    explicit WriteResult(ssize_t ret) : writeReturn(ret) {}
+
+    WriteResult(ssize_t ret, std::unique_ptr<const AsyncSocketException> e)
+        : writeReturn(ret), exception(std::move(e)) {}
+
+    ssize_t writeReturn;
+    std::unique_ptr<const AsyncSocketException> exception;
+  };
+
+  /**
+   * readReturn is the number of bytes read, or READ_EOF on EOF, or
+   * READ_ERROR on error, or READ_BLOCKING if the operation will
+   * block.
+   * exception is a more specific exception that may have caused a read error.
+   * Not all read errors have exceptions associated with them thus readReturn
+   * should be checked to determine whether the operation resulted in an error.
+   */
+  struct ReadResult {
+    explicit ReadResult(ssize_t ret) : readReturn(ret) {}
+
+    ReadResult(ssize_t ret, std::unique_ptr<const AsyncSocketException> e)
+        : readReturn(ret), exception(std::move(e)) {}
+
+    ssize_t readReturn;
+    std::unique_ptr<const AsyncSocketException> exception;
+  };
+
   /**
    * A WriteRequest object tracks information about a pending write operation.
    */
@@ -529,7 +565,7 @@ class AsyncSocket : virtual public AsyncTransportWrapper {
 
     virtual void destroy() = 0;
 
-    virtual bool performWrite() = 0;
+    virtual WriteResult performWrite() = 0;
 
     virtual void consume() = 0;
 
@@ -579,6 +615,10 @@ class AsyncSocket : virtual public AsyncTransportWrapper {
     READ_NO_ERROR = -3,
   };
 
+  enum WriteResultEnum {
+    WRITE_ERROR = -1,
+  };
+
   /**
    * Protected destructor.
    *
@@ -683,11 +723,9 @@ class AsyncSocket : virtual public AsyncTransportWrapper {
    * @param buf      The buffer to read data into.
    * @param buflen   The length of the buffer.
    *
-   * @return Returns the number of bytes read, or READ_EOF on EOF, or
-   * READ_ERROR on error, or READ_BLOCKING if the operation will
-   * block.
+   * @return Returns a read result. See read result for details.
    */
-  virtual ssize_t performRead(void** buf, size_t* buflen, size_t* offset);
+  virtual ReadResult performRead(void** buf, size_t* buflen, size_t* offset);
 
   /**
    * Populate an iovec array from an IOBuf and attempt to write it.
@@ -736,12 +774,14 @@ class AsyncSocket : virtual public AsyncTransportWrapper {
    *                          will contain the number of bytes written in the
    *                          partially written iovec entry.
    *
-   * @return Returns the total number of bytes written, or -1 on error.  If no
-   *     data can be written immediately, 0 is returned.
+   * @return Returns a WriteResult. See WriteResult for more details.
    */
-  virtual ssize_t performWrite(const iovec* vec, uint32_t count,
-                               WriteFlags flags, uint32_t* countWritten,
-                               uint32_t* partialWritten);
+  virtual WriteResult performWrite(
+      const iovec* vec,
+      uint32_t count,
+      WriteFlags flags,
+      uint32_t* countWritten,
+      uint32_t* partialWritten);
 
   bool updateEventRegistration();