Use SIGIO for signal-driven user input. Now, using SIGALRM and SIGIO

allows all the advantages of the Win32 threaded model with about half the
calories.

src/odoors/ODKrnl.c

@@ -73,7 +73,11 @@
 
 #include "OpenDoor.h"
 #ifdef ODPLAT_NIX
+#include <sys/types.h>
+#include <unistd.h>
 #include <signal.h>
+#include <fcntl.h>
+#include <errno.h>
 #endif
 #include "ODCore.h"
 #include "ODGen.h"
@@ -108,7 +112,8 @@ static void ODKrnlTimeUpdate(void);
 static void ODKrnlChatCleanup(void);
 static void ODKrnlChatMode(void);
 #ifdef ODPLAT_NIX
-void sig_run_kernel(int sig);
+static void sig_run_kernel(int sig);
+static void sig_get_char(int sig);
 #endif
 
 /* Functions specific to the multithreaded implementation of the kernel. */
@@ -187,7 +192,7 @@ tODResult ODKrnlInitialize(void)
 
    /* Run kernel on SIGALRM (Every 1 second) */
    act.sa_handler=sig_run_kernel;
-   act.sa_flags=0;
+   act.sa_flags=SA_RESTART;
    sigemptyset(&(act.sa_mask));
    sigaction(SIGALRM,&act,NULL);
    itv.it_interval.tv_sec=1;
@@ -195,6 +200,28 @@ tODResult ODKrnlInitialize(void)
    itv.it_value.tv_sec=0;
    itv.it_value.tv_usec=250000;
    setitimer(ITIMER_REAL,&itv,NULL);
+   
+   /* Make sure SIGALRM is unblocked */
+   sigemptyset(&block);
+   sigaddset(&block,SIGALRM);
+   sigprocmask(SIG_UNBLOCK,&block,NULL);
+
+   /* Make stdin signal driven. */
+   act.sa_handler=sig_get_char;
+   act.sa_flags=0;
+   sigemptyset(&(act.sa_mask));
+   sigaction(SIGIO,&act,NULL);
+
+   /* Make sure SIGIO is unblocked */
+   sigemptyset(&block);
+   sigaddset(&block,SIGIO);
+   sigprocmask(SIG_UNBLOCK,&block,NULL);
+   
+   /* Have SIGIO signales delivered to this process */
+   fcntl(0,F_SETOWN,getpid());
+   
+   /* Enable SIGIO when read possible on stdin */
+   fcntl(0,F_SETFL,fcntl(0,F_GETFL)|O_ASYNC);
 #endif
 
    /* Initialize time of next status update and next time deduction. */
@@ -354,12 +381,14 @@ ODAPIDEF void ODCALL od_kernel(void)
          }
       }
 
+#ifndef ODPLAT_NIX	/* On *nix, this is handled by a signal */
       /* Loop, obtaining any new characters from the serial port and */
       /* adding them to the common local/remote input queue.         */
       while(ODComGetByte(hSerialPort, &ch, FALSE) == kODRCSuccess)
       {
          ODKrnlHandleReceivedChar(ch, TRUE);
       }
+#endif
    }
 
 #ifdef ODPLAT_DOS
@@ -1590,17 +1619,32 @@ static void ODKrnlChatCleanup(void)
 #endif
 }
 
+#ifdef ODPLAT_NIX
 /* ----------------------------------------------------------------------------
  * sig_run_kernel(sig)				   *** PRIVATE FUNCTION ***
  *
  * Runs od_kernel() on a SIGALRM
  *
  */
-#ifdef ODPLAT_NIX
-void sig_run_kernel(int sig)
+static void sig_run_kernel(int sig)
 {
    od_kernel();
 }
-#endif
-
 
+/* ----------------------------------------------------------------------------
+ * sig_run_kernel(sig)				   *** PRIVATE FUNCTION ***
+ *
+ * Runs od_kernel() on a SIGALRM
+ *
+ */
+static void sig_get_char(int sig)
+{
+   static char ch;
+   /* Loop, obtaining any new characters from the serial port and */
+   /* adding them to the common local/remote input queue.         */
+   while(ODComGetByte(hSerialPort, &ch, FALSE) == kODRCSuccess)
+   {
+      ODKrnlHandleReceivedChar(ch, TRUE);
+   }
+}
+#endif

src/odoors/ODPlat.c

@@ -660,16 +660,20 @@ void ODTimerWaitForElapse(tODTimer *pTimer)
    }
 
 #elif defined(ODPLAT_NIX)
-   gettimeofday(&tv,NULL);
-   tv.tv_sec -= pTimer->Start.tv_sec;
-   tv.tv_usec -= pTimer->Start.tv_usec;
-   if(tv.tv_usec < 0) {
-      tv.tv_sec--;
-	  tv.tv_usec += 1000000;
+   /* This is timing sensitive and *MUST* wait regardless of 100% CPU or signals */
+   while(1)  {
+      gettimeofday(&tv,NULL);
+      tv.tv_sec -= (pTimer->Start.tv_sec + pTimer->Duration/1000);
+      tv.tv_usec -= (pTimer->Start.tv_usec + ((pTimer->Duration*1000)%1000000));
+      if(tv.tv_usec < 0) {
+         tv.tv_sec--;
+         tv.tv_usec += 1000000;
+      }
+      if(tv.tv_sec<0 || tv.tv_usec<0)
+         return;
+      if(!select(0,NULL,NULL,NULL,&tv))
+	     break;
    }
-   if(tv.tv_sec<0 || tv.tv_usec<0)
-      return;
-   select(0,NULL,NULL,NULL,&tv);
 #else /* !ODPLAT_DOS */
    {
       /* Under other platforms, timer resolution is high enough that we can */
@@ -779,7 +783,7 @@ ODAPIDEF void ODCALL od_sleep(tODMilliSec Milliseconds)
 {
 #ifdef ODPLAT_NIX
    struct timeval tv;
-   fd_set in;
+   struct timeval start;
 #endif
    /* Log function entry if running in trace mode. */
    TRACE(TRACE_API, "od_sleep()");
@@ -811,16 +815,33 @@ ODAPIDEF void ODCALL od_sleep(tODMilliSec Milliseconds)
 #endif /* ODPLAT_WIN32 */
 
 #ifdef ODPLAT_NIX
-   FD_ZERO(&in);
-   tv.tv_sec=Milliseconds/1000;
-   tv.tv_usec=(Milliseconds%1000)*1000;
    if(Milliseconds==0)  {
-      tv.tv_usec=1000;
-      FD_SET(0,&in);
+      /* Prevent 100% CPU *only* no delay is actually required here */
+      tv.tv_sec=0;
+      tv.tv_usec=1;
+      select(0,NULL,NULL,NULL,&tv);
+   }
+   else  {
+      gettimeofday(&start,NULL);
+	  start.tv_sec += Milliseconds/1000;
+	  start.tv_usec += (Milliseconds*1000)%1000000;
+
+
+      while(1)  {
+	     /* This is timing sensitive and *MUST* wait for at least Milliseconds regardless of 100% CPU or signals */
+         gettimeofday(&tv,NULL);
+         tv.tv_sec -= (start.tv_sec + Milliseconds/1000);
+         tv.tv_usec -= (start.tv_usec + ((Milliseconds*1000)%1000000));
+         if(tv.tv_usec < 0) {
+            tv.tv_sec--;
+            tv.tv_usec += 1000000;
+         }
+         if(tv.tv_sec<0 || tv.tv_usec<0)
+            break;
+         if(!select(0,NULL,NULL,NULL,&tv))
+            break;
+      }
    }
-
-   if(select(1,Milliseconds?NULL:&in,NULL,NULL,&tv)>0)
-      od_kernel();
 #endif
 
    OD_API_EXIT();

src/odoors/README.NIX

+Note that OpenDoors installs signal handlers and *REQUIRES* that they be called
+for the following signals:
+
+SIGALRM - Drives the od_kernel
+SIGIO   - Drives user input
+
+If you install your own handles, be absolutely sure that they call the old
+handlers as well.