select interrupt cleanup

ixwebsocket/IXSelectInterruptPipe.cpp

@@ -0,0 +1,108 @@
+/*
+ *  IXEventFd.cpp
+ *  Author: Benjamin Sergeant
+ *  Copyright (c) 2018-2019 Machine Zone, Inc. All rights reserved.
+ */
+
+//
+// On macOS we use UNIX pipes to wake up select.
+//
+
+#include "IXSelectInterruptPipe.h"
+
+#include <unistd.h> // for write
+#include <string.h> // for strerror
+#include <fcntl.h>
+#include <errno.h>
+#include <sstream>
+
+namespace ix
+{
+    // File descriptor at index 0 in _fildes is the read end of the pipe
+    // File descriptor at index 1 in _fildes is the write end of the pipe
+    const int SelectInterruptPipe::kPipeReadIndex = 0;
+    const int SelectInterruptPipe::kPipeWriteIndex = 1;
+
+    SelectInterruptPipe::SelectInterruptPipe()
+    {
+        ;
+    }
+
+    SelectInterruptPipe::~SelectInterruptPipe()
+    {
+        ::close(_fildes[kPipeReadIndex]);
+        ::close(_fildes[kPipeWriteIndex]);
+        _fildes[kPipeReadIndex] = -1;
+        _fildes[kPipeWriteIndex] = -1;
+    }
+
+    bool SelectInterruptPipe::init(std::string& errorMsg)
+    {
+        _fildes[kPipeReadIndex] = -1;
+        _fildes[kPipeWriteIndex] = -1;
+
+        if (pipe(_fildes) < 0)
+        {
+            std::stringstream ss;
+            ss << "SelectInterruptPipe::init() failed in pipe() call"
+               << " : " << strerror(errno);
+            errorMsg = ss.str();
+            return false;
+        }
+
+        if (fcntl(_fildes[kPipeReadIndex], F_SETFL, O_NONBLOCK) == -1)
+        {
+            std::stringstream ss;
+            ss << "SelectInterruptPipe::init() failed in fcntl() call"
+               << " : " << strerror(errno);
+            errorMsg = ss.str();
+
+            _fildes[kPipeReadIndex] = -1;
+            _fildes[kPipeWriteIndex] = -1;
+            return false;
+        }
+
+        if (fcntl(_fildes[kPipeWriteIndex], F_SETFL, O_NONBLOCK) == -1)
+        {
+            std::stringstream ss;
+            ss << "SelectInterruptPipe::init() failed in fcntl() call"
+               << " : " << strerror(errno);
+            errorMsg = ss.str();
+
+            _fildes[kPipeReadIndex] = -1;
+            _fildes[kPipeWriteIndex] = -1;
+            return false;
+        }
+
+        return true;
+    }
+
+    bool SelectInterruptPipe::notify(uint64_t value)
+    {
+        int fd = _fildes[kPipeWriteIndex];
+        if (fd == -1) return false;
+
+        // we should write 8 bytes for an uint64_t
+        return write(fd, &value, sizeof(value)) == 8;
+    }
+
+    // TODO: return max uint64_t for errors ?
+    uint64_t SelectInterruptPipe::read()
+    {
+        int fd = _fildes[kPipeReadIndex];
+
+        uint64_t value = 0;
+        ::read(fd, &value, sizeof(value));
+        return value;
+    }
+
+    bool SelectInterruptPipe::clear()
+    {
+        return true;
+    }
+
+    int SelectInterruptPipe::getFd()
+    {
+        return _fildes[kPipeReadIndex];
+    }
+}