[llvm] [llvm][Support] Implement raw_socket_stream::read with optional timeout (PR #92308)

[Michael Spencer via llvm-commits]

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@@ -124,11 +125,28 @@ class raw_socket_stream : public raw_fd_stream {
 
 public:
   raw_socket_stream(int SocketFD);
+  ~raw_socket_stream();
+
   /// Create a \p raw_socket_stream connected to the UNIX domain socket at \p
   /// SocketPath.
   static Expected<std::unique_ptr<raw_socket_stream>>
   createConnectedUnix(StringRef SocketPath);
-  ~raw_socket_stream();
+
+  /// Attempt to read from the raw_socket_stream's file descriptor.
+  ///
+  /// This method can optionally either block until data is read or an error has
+  /// occurred or timeout after a specified amount of time has passed. By
+  /// default the method will block until the socket has read data or
+  /// encountered an error. If the read times out this method will return
+  /// std::errc:timed_out
+  ///
+  /// \param Ptr The start of the buffer that will hold any read data
+  /// \param Size The number of bytes to be read
+  /// \param Timeout An optional timeout duration in milliseconds
+  ///
+  llvm::Expected<ssize_t>
+  read(char *Ptr, size_t Size,
+       std::chrono::milliseconds Timeout = std::chrono::milliseconds(-1));
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Bigcheese wrote:

This should use the same error handling as `raw_fd_stream::read`. It would be nice to move all of `raw_ostream` to `Expected`, but for an overload I think it's best to match the behavior.

https://github.com/llvm/llvm-project/pull/92308