communicate implemented - test case not working though

subprocess.hpp

@@ -8,6 +8,7 @@
 #include <vector>
 #include <sstream>
 #include <memory>
+#include <thread>
 #include <initializer_list>
 #include <exception>
 
@@ -20,13 +21,14 @@ extern "C" {
 
 namespace subprocess {
 
-using Buffer    = std::vector<uint8_t>;
-using OutBuffer = std::vector<uint8_t>;
-using ErrBuffer = std::vector<uint8_t>;
+using Buffer    = std::vector<char>;
+using OutBuffer = std::vector<char>;
+using ErrBuffer = std::vector<char>;
 
 // Max buffer size allocated on stack for read error
 // from pipe
 static const size_t SP_MAX_ERR_BUF_SIZ = 1024;
+static const size_t DEFAULT_BUF_CAP_BYTES = 8192; 
 
 // Exception Classes
 class CalledProcessError: public std::runtime_error
@@ -320,12 +322,24 @@ public:
   {}
   void operator=(const Communication&) = delete;
 public:
-  int send(const uint8_t* msg, size_t length);
+  int send(const char* msg, size_t length);
   int send(const Buffer& msg);
-  int send(Buffer&& msg);
+
+  std::pair<OutBuffer, ErrBuffer> communicate(const char* msg, size_t length);
+  std::pair<OutBuffer, ErrBuffer> communicate(const Buffer& msg)
+  { return communicate(msg.data(), msg.size()); }
+
+  void set_out_buf_cap(size_t cap) { out_buf_cap_ = cap; }
+  void set_err_buf_cap(size_t cap) { err_buf_cap_ = cap; }
+
+private:
+  std::pair<OutBuffer, ErrBuffer> communicate_threaded(
+      const char* msg, size_t length);
 
 private:
   Streams* stream_;
+  size_t out_buf_cap_ = DEFAULT_BUF_CAP_BYTES;
+  size_t err_buf_cap_ = DEFAULT_BUF_CAP_BYTES;
 };
 
 class Streams
@@ -372,15 +386,22 @@ public:
   void output(FILE* fp) { output_.reset(fp, fclose); }
   void error(FILE* fp)  { error_.reset(fp, fclose); }
 
+  void set_out_buf_cap(size_t cap) { comm_.set_out_buf_cap(cap); }
+  void set_err_buf_cap(size_t cap) { comm_.set_err_buf_cap(cap); }
+
 public: /* Communication forwarding API's */
-  int send(const uint8_t* msg, size_t length)
+  int send(const char* msg, size_t length)
   { return comm_.send(msg, length); }
 
   int send(const Buffer& msg)
   { return comm_.send(msg); }
 
-  int send(Buffer&& msg)
-  { return comm_.send(std::move(msg)); }
+  std::pair<OutBuffer, ErrBuffer> communicate(const char* msg, size_t length)
+  { return comm_.communicate(msg, length); }
+
+  std::pair<OutBuffer, ErrBuffer> communicate(const Buffer& msg)
+  { return comm_.communicate(msg); }
+
 
 public:// Yes they are public
 
@@ -441,22 +462,21 @@ public:
 
   int pid() const noexcept { return child_pid_; }
 
-  void set_out_buf_cap();
+  void set_out_buf_cap(size_t cap) { stream_.set_out_buf_cap(cap); }
 
-  void set_err_buf_cap();
+  void set_err_buf_cap(size_t cap) { stream_.set_err_buf_cap(cap); }
 
-  int send(const uint8_t* msg, size_t length) 
+  int send(const char* msg, size_t length) 
   { return stream_.send(msg, length); }
 
   int send(const Buffer& msg)
   { return stream_.send(msg); }
 
-  int send(Buffer&& msg)
-  { return stream_.send(std::move(msg)); }
+  std::pair<OutBuffer, ErrBuffer> communicate(const char* msg, size_t length)
+  { return stream_.communicate(msg, length); }
 
-  void communicate(const char* msg, size_t length, bool finish = false);
-  void communicate(const Buffer& msg, bool finish = false);
-  void communicate(Buffer&& msg, bool finish = false);
+  std::pair<OutBuffer, ErrBuffer> communicate(const Buffer& msg)
+  { return stream_.communicate(msg); }
 
 private:
   template <typename F, typename... Args>
@@ -729,10 +749,10 @@ namespace detail {
     }
   }
 
-  int Communication::send(const uint8_t* msg, size_t length)
+  int Communication::send(const char* msg, size_t length)
   {
     if (stream_->input() == nullptr) return -1;
-    return std::fwrite(msg, sizeof(uint8_t), length, stream_->input());
+    return std::fwrite(msg, sizeof(char), length, stream_->input());
   }
 
   int Communication::send(const Buffer& msg)
@@ -740,9 +760,96 @@ namespace detail {
     return send(msg.data(), msg.size());
   }
 
-  int Communication::send(Buffer&& msg)
+  std::pair<OutBuffer, ErrBuffer>
+  Communication::communicate(const char* msg, size_t length)
   {
-    return send(msg.data(), msg.size());
+    // Optimization from subprocess.py
+    // If we are using one pipe, or no pipe
+    // at all, using select() or threads is unnecessary.
+    auto hndls = {stream_->input(), stream_->output(), stream_->error()};
+    int count = std::count(std::begin(hndls), std::end(hndls), nullptr);
+
+    if (count >= 2) {
+      OutBuffer obuf;
+      ErrBuffer ebuf;
+      if (stream_->input()) {
+      	if (msg) {
+	  int wbytes = std::fwrite(msg, sizeof(char), length, stream_->input());
+	  if (wbytes < length) {
+	    if (errno != EPIPE && errno != EINVAL) {
+	      throw OSError("fwrite error", errno);
+	    }
+	  }
+	}
+	// Close the input stream
+	stream_->input_.reset();
+      } else if (stream_->output()) {
+      	// Read till EOF
+      	// ATTN: This could be blocking, if the process
+      	// at the other end screws up, we get screwed up as well
+      	obuf.resize(out_buf_cap_);
+	int rbytes = util::read_atmost_n(fileno(stream_->output()),
+	    (char*)obuf.data(), obuf.size());
+	if (rbytes == -1) {
+	  throw OSError("read to obuf failed", errno);
+	}
+	// Close the output stream
+	stream_->output_.reset();
+      } else if (stream_->error()) {
+      	// Same screwness applies here as well
+      	ebuf.resize(err_buf_cap_);
+      	int rbytes = util::read_atmost_n(fileno(stream_->error()),
+      	    (char*)ebuf.data(), ebuf.size());
+      	if (rbytes == -1) {
+      	  throw OSError("read to ebuf failed", errno);
+	}
+	// Close the error stream
+	stream_->error_.reset();
+      }
+      return std::make_pair(obuf, ebuf);
+    }
+
+    return communicate_threaded(msg, length);
+  }
+
+
+  std::pair<OutBuffer, ErrBuffer>
+  Communication::communicate_threaded(const char* msg, size_t length)
+  {
+    OutBuffer obuf;
+    ErrBuffer ebuf;
+
+    std::vector<std::thread> bg_threads;
+
+    if (stream_->output()) {
+      obuf.resize(out_buf_cap_);
+      bg_threads.push_back(std::thread(
+      	    util::read_atmost_n, fileno(stream_->output()),
+      	    (char*)obuf.data(), obuf.size()));
+    }
+    if (stream_->error()) {
+      ebuf.resize(err_buf_cap_);
+      bg_threads.push_back(std::thread(
+      	  util::read_atmost_n, fileno(stream_->error()),
+      	  (char*)ebuf.data(), ebuf.size()));
+    }
+    if (stream_->input()) {
+      if (msg) {
+	int wbytes = std::fwrite(msg, sizeof(char), length, stream_->input());
+	if (wbytes < length) {
+	  if (errno != EPIPE && errno != EINVAL) {
+	    for (auto& t: bg_threads) t.join();
+	    throw OSError("fwrite error", errno);
+	  }
+	}
+      }
+      stream_->input_.reset();
+    }
+
+    // Wait for the threads to finish
+    for(auto& thr : bg_threads) thr.join();
+
+    return std::make_pair(obuf, ebuf);
   }
 
 }; // end namespace detail

test/test_subprocess.cc

@@ -6,12 +6,10 @@ using namespace subprocess;
 void test_input()
 {
   auto p = Popen({"grep", "f"}, output{PIPE}, input{PIPE});
-  const char* msg = "one\ntwo\nfour\n";
-  std::fwrite(msg, 1, strlen(msg), p.input());
-  fclose (p.input());
-
-  std::vector<uint8_t> rbuf(128);
-  std::fread(rbuf.data(), 1, 128, p.output());
+  const char* msg = "one\two\three\four\five\n";
+  p.send(msg, strlen(msg));
+  auto res = p.communicate(nullptr, 0);
+  std::cout << res.first.data() << std::endl;
 }
 
 int main() {