README.md

Linux and Windows implementation of shared memory and semaphores

How to use

Semaphores (interprocess):

Process1: Initialize a semaphore, and Add to semaphores set (semaphore 0 in example) value 1. And start doing some interprocess work (write to the shared memory for example).

s, err := NewSemaphore(0x12334, 1, 0666, true, IPC_CREAT)
if err != nil {
	panic(err)
}
err = s.Add(0)
if err != nil {
	panic(err)
}

After work will be done, just unlock semaphore:

err = s.Done(0) // 0 here is the 1-st semaphore in the set identified by semaphore ID.
  if err != nil {
  	panic(err)
  }

Process2: Attach to the same semaphore. And Wait until Process1 released semaphore.

  s, err := NewSemaphore(0x12334, 1, 0666, false, IPC_CREAT)
  if err != nil {
  	panic(err)
  }
  err = s.Wait()
  if err != nil {
  	panic(err)
  }

Shared Memory (interprocess):

Initialize shared memory segment with a key, required size and flags:

seg1, err := NewSharedMemorySegment(0x1, 1024, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP, IPC_CREAT)
if err != nil {
	t.Fatal(err)
}

Write the specified amount of data and detach from the segment:

// write data to the shared memory
// testData is less or equal to 1024 specified in prev declaration 
seg1.Write([]byte(testData))
err = seg1.Detach()
if err != nil {
	t.Fatal(err)
}

From the another process, initialize shared memory segment with the same key, size, but with ReadOnly flag:

seg2, err := NewSharedMemorySegment(0x1, 1024, 0, SHM_RDONLY)
if err != nil {
	t.Fatal(err)
}

Read specified amount of data and detach from the segment:

buf := make([]byte, len(testData), len(testData))
err = seg2.Read(buf)
if err != nil {
	t.Fatal(err)
}
err = seg2.Detach()
if err != nil {
	t.Fatal(err)
}