[R-gregmisc-users] SF.net SVN: r-gregmisc: [1043] trunk/fork

[<wa...@us...>]

Revision: 1043
          http://svn.sourceforge.net/r-gregmisc/?rev=1043&view=rev
Author:   warnes
Date:     2007-02-05 15:08:43 -0800 (Mon, 05 Feb 2007)

Log Message:
-----------
Add signal() command to allow ignoring signals

Modified Paths:
--------------
    trunk/fork/DESCRIPTION
    trunk/fork/R/signame.R
    trunk/fork/man/fork.Rd
    trunk/fork/man/signame.Rd
    trunk/fork/src/fork.c

Added Paths:
-----------
    trunk/fork/R/signal.R
    trunk/fork/man/signal.Rd

Modified: trunk/fork/DESCRIPTION
===================================================================
--- trunk/fork/DESCRIPTION	2007-01-28 10:42:24 UTC (rev 1042)
+++ trunk/fork/DESCRIPTION	2007-02-05 23:08:43 UTC (rev 1043)
@@ -1,6 +1,6 @@
 Package: fork
 Title: R functions for handling multiple processes.
-Version: 1.0.2
+Version: 1.0.3
 Author: Gregory R. Warnes <wa...@bs...>
 Description: These functions  provides simple wrappers around the Unix process 
     management API calls: fork, wait, waitpid, kill, and _exit.  This

Added: trunk/fork/R/signal.R
===================================================================
--- trunk/fork/R/signal.R	                        (rev 0)
+++ trunk/fork/R/signal.R	2007-02-05 23:08:43 UTC (rev 1043)
@@ -0,0 +1,30 @@
+# $Id: kill.R 340 2004-05-25 19:12:32Z warnes $
+
+signal <- function(signal, action=c("ignore","restore") )
+  {
+    action=match.args(action)
+    
+    if(is.character(signal))
+      sig=sigval(signal)$val
+    else (is.numeric(signal) && !is.na(signal))
+      sig=signal
+    else
+      stop("Illegal value for signal")
+    
+    act <- switch(
+                  action,
+                  "ignore"=0,
+                  "restore"=1
+                  )
+
+    msg1 = 
+    
+    .C(
+       "Rfork_signal",
+       as.integer(signal),
+       as.integer(act),
+       PACKAGE="fork"
+       )
+    invisible()
+  }
+

Modified: trunk/fork/R/signame.R
===================================================================
--- trunk/fork/R/signame.R	2007-01-28 10:42:24 UTC (rev 1042)
+++ trunk/fork/R/signame.R	2007-02-05 23:08:43 UTC (rev 1043)
@@ -20,7 +20,8 @@
                  val=integer(1),
                  desc=character(1),
                  PACKAGE="fork")
-    unlist(retval)
+    #retval <- unlist(retval)
+    retval
   }
 
 siglist <- function()

Modified: trunk/fork/man/fork.Rd
===================================================================
--- trunk/fork/man/fork.Rd	2007-01-28 10:42:24 UTC (rev 1042)
+++ trunk/fork/man/fork.Rd	2007-02-05 23:08:43 UTC (rev 1043)
@@ -162,8 +162,15 @@
      close(con2)
   }
 
+# Important: if we aren't going to explicitly wait() for the child
+# process to exit, we need to tell the OS that we are ignoring child
+# process signals so it will let us die cleanly.
+signal("SIGCHLD","ignore")
 
+# fork off the process
 pid <- fork(recieve)
+
+# start sending...
 send()
 }
 }

Added: trunk/fork/man/signal.Rd
===================================================================
--- trunk/fork/man/signal.Rd	                        (rev 0)
+++ trunk/fork/man/signal.Rd	2007-02-05 23:08:43 UTC (rev 1043)
@@ -0,0 +1,49 @@
+\name{signal}
+\alias{signal}
+\title{Enable or disable handling of signals}
+\description{ 
+  This function allows enabling or disabling handling of the specified signal.
+}
+\usage{
+signal(signal, action = c("ignore", "default"))
+}
+\arguments{
+  \item{signal}{Signal handler to manipulate, either as a numeric id or
+    character mnemonic}
+  \item{action}{Either "ignore" or "default"}
+}
+\details{
+  It is occasionally necessary to instruct the R process to ignore
+  certain signals.  This function allows changing the status of a signal
+  to either igore the signal (SIG_IGN="ignore") or to the OS's default
+  handler (SIG_DFL="default")  
+}
+\value{
+  Nothing of interest.
+}
+\references{ See the unix man page for "signal" for more information}
+\author{Gregory R. Warnes \email{gre...@ro...} }
+\note{
+  Be very careful with this function.  It can be used to totally
+  confuse the R process.
+}
+\seealso{  \code{\link{sigval}}, \code{\link{fork}} }
+\examples{
+
+# Ignore child termination signals for forked processes
+signal("SIGCHLD","ignore")
+
+# Fork off a child process to say "Hi!".
+ {
+    pid = fork(slave=NULL) 
+    if(pid==0) {
+      # only runs in the child process
+      cat("Hi from the child process!\n");
+      exit() # force process to die
+    } 
+ } 
+
+}
+% Add one or more standard keywords, see file 'KEYWORDS' in the
+% R documentation directory.
+\keyword{programming}

Modified: trunk/fork/man/signame.Rd
===================================================================
--- trunk/fork/man/signame.Rd	2007-01-28 10:42:24 UTC (rev 1042)
+++ trunk/fork/man/signame.Rd	2007-02-05 23:08:43 UTC (rev 1043)
@@ -22,7 +22,7 @@
   compile time.
 }
 \value{
-  A vector (\code{signame}, \code{sigval}) or data frame
+  A list (\code{signame}, \code{sigval}) or data frame
   (\code{siglist}) containing the components:
   \item{name}{Symbolic name}
   \item{val}{Integer value}

Modified: trunk/fork/src/fork.c
===================================================================
--- trunk/fork/src/fork.c	2007-01-28 10:42:24 UTC (rev 1042)
+++ trunk/fork/src/fork.c	2007-02-05 23:08:43 UTC (rev 1043)
@@ -266,3 +266,15 @@
   return list; 
 } 
 
+void Rfork_signal(int *sig, int *action)
+{
+  sig_t func;
+
+  if(*action==0)
+    func = SIG_IGN;
+  else
+    func = SIG_DFL;
+
+  signal( *sig, func );
+}
+   


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