Up some limits on !windows.

This is needed on OSX and possibly others.

ok davec

btcd.go

@@ -157,8 +157,14 @@ func main() {
 	// Use all processor cores.
 	runtime.GOMAXPROCS(runtime.NumCPU())
 
+	// Up some limits.
+	err := setLimits()
+	if err != nil {
+		os.Exit(1)
+	}
+
 	// Work around defer not working after os.Exit()
-	err := btcdMain()
+	err = btcdMain()
 	if err != nil {
 		os.Exit(1)
 	}

limits_unix.go

@@ -0,0 +1,50 @@
+// Copyright (c) 2013 Conformal Systems LLC.
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+// +build !windows
+
+package main
+
+import (
+	"fmt"
+	"syscall"
+)
+
+const (
+	fileLimitWant = 2048
+	fileLimitMin  = 1024
+)
+
+func setLimits() error {
+	var rLimit syscall.Rlimit
+
+	err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rLimit)
+	if err != nil {
+		return err
+	}
+	if rLimit.Cur > fileLimitWant {
+		return nil
+	}
+	if rLimit.Max < fileLimitMin {
+		err = fmt.Errorf("need at least %v file descriptors",
+			fileLimitMin)
+		return err
+	}
+	if rLimit.Max < fileLimitWant {
+		rLimit.Cur = rLimit.Max
+	} else {
+		rLimit.Cur = fileLimitWant
+	}
+	err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rLimit)
+	if err != nil {
+		// try min value
+		rLimit.Cur = fileLimitMin
+		err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rLimit)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

limits_windows.go

@@ -0,0 +1,9 @@
+// Copyright (c) 2013 Conformal Systems LLC.
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package main
+
+func setLimits() error {
+	return nil
+}