It mostly works

Author: bob5972

Makefile

@@ -14,6 +14,7 @@ DEPDIR=$(DEPROOT)
 TARGET=job-server
 
 #The BUILDROOT folder is included for config.h
+WARNINGS = -Wall -Wno-unused-but-set-variable
 CFLAGS = ${DEFAULT_CFLAGS} -I $(BUILDROOT) $(INCLUDE_FLAGS)
 CPPFLAGS = ${CFLAGS}
 

configure

@@ -63,7 +63,7 @@ echo '#define DEBUG ' $DEBUG >> $CONFIG_H
 echo DEBUG=$DEBUG >> $CONFIG_MK;
 
 if [ "$DEBUG" != "0" ]; then
-	DEFAULT_CFLAGS="${DEFAULT_CFLAGS} -Werror -Wall -g"
+	DEFAULT_CFLAGS="${DEFAULT_CFLAGS} -Werror -g"
 else
 	if [ "$DEFAULT_CFLAGS" == "" ]; then
 		DEFAULT_CFLAGS="-march=native -O2 -fomit-frame-pointer"

main.cpp

@@ -6,21 +6,118 @@
 
 #include <stdio.h>
 #include <iostream>
+#include <sys/sysinfo.h>
+#include <sys/types.h>
+#include <sys/wait.h>
 
 #include "MBString.h"
+#include "MBVector.h"
 
 using namespace std;
 
+#define PID_INVALID (-1)
+
+typedef struct MainData {
+	MBVector<pid_t> children;
+	int numJobs;
+} MainData;
+
+static MainData mainData;
+
+static void
+InsertChild(pid_t pid)
+{
+	for (int x = 0; x < mainData.children.size(); x++) {
+		if (mainData.children[x] == PID_INVALID) {
+			mainData.children[x] = pid;
+			return;
+		}
+	}
+	
+	NOT_REACHED();
+}
+
+static void
+WaitForChild(void)
+{
+	int status;
+	int result;
+	pid_t pid;
+	
+	for (int x = 0; x < mainData.children.size(); x++) {
+		if (mainData.children[x] == PID_INVALID) {
+			return;
+		}
+	}
+	
+	//No free slot
+	for (int x = 0; x < mainData.children.size(); x++) {
+		pid = mainData.children[x];
+		ASSERT(pid != PID_INVALID);
+		
+		result = waitpid(pid, &status, WNOHANG);
+		if (result == -1) {			
+			Warning("%s: Error occured while waiting for child.\n");
+		} else if (WIFEXITED(status)) {
+			mainData.children[x] = PID_INVALID;
+			return;
+		}
+	}
+	
+	// All children are still running...
+	Warning("%s: Waiting for any child...\n", __FUNCTION__);
+	pid = wait(&status);	
+	if (pid != -1) {
+		for (int x = 0; x < mainData.children.size(); x++) {
+			if (mainData.children[x] == pid) {
+				mainData.children[x] = PID_INVALID;
+				return;
+			}
+		}
+		ASSERT(FALSE); // We didn't find our child??
+	}
+	
+	Warning("%s", "Didn't find a free child... Trying again.\n");
+	WaitForChild();
+}
+
 int main()
 {
 	MBString line;
+	pid_t pid;
+	
+	mainData.numJobs = get_nprocs();
+	mainData.children.resize(mainData.numJobs);
+	
+	for (int x = 0; x < mainData.numJobs; x++) {
+		mainData.children[x] = PID_INVALID;
+	}
 
 	while (!cin.eof()) {
 		printf("> ");
 		MBString_GetLine(cin, line);
-		if (!line.isEmpty()) {
-			printf("Executing: %s\n", line.cstr());
-			system(line.cstr());
+		if (!line.isEmpty()) {			
+			WaitForChild();
+				
+			pid = fork();
+			if (!pid) {
+				// We are the child
+				system(line.cstr());
+				exit(0);
+			} else {
+				// We are the parent
+				Warning("%s: Launched [%d] %s\n", __FUNCTION__, pid, line.cstr());//banackm
+				InsertChild(pid);
+			}
+		}
+	}
+	
+	// Wait for any remaining children.
+	for (int x = 0; x < mainData.children.size(); x++) {
+		pid = mainData.children[x];
+		if (pid != PID_INVALID) {
+			printf("%s: Waiting for %d\n", __FUNCTION__, pid);//banackm
+			waitpid(pid, NULL, 0);
 		}
 	}
 

test.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/perl
+
+
+open JOBSERVER, "| build/job-server";
+
+print JOBSERVER "./work.sh 5\n";
+print JOBSERVER "./work.sh 3\n";
+print JOBSERVER "./work.sh 6\n";
+print JOBSERVER "./work.sh 7\n";
+print JOBSERVER "./work.sh 8\n";
+print JOBSERVER "./work.sh 9\n";
+print JOBSERVER "./work.sh 10\n";
+print JOBSERVER "./work.sh 11\n";
+
+close JOBSERVER
+
+
+

work.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+
+echo Starting $*
+sleep $1
+echo Ending $*
+
+exit 0
+