structured main routines. implement file reporter

metrics/disk_io.sh

@@ -1,12 +1,17 @@
 #!/bin/sh
 
-if [ -z $DISK_IO_MOUNTPOINT ]; then
-  if is_osx; then
-    DISK_IO_MOUNTPOINT="disk0"
-  else
-    DISK_IO_MOUNTPOINT="/dev/vda"
+init () {
+  if [ -z $DISK_IO_MOUNTPOINT ]; then
+    if is_osx; then
+      DISK_IO_MOUNTPOINT="disk0"
+    else
+      DISK_IO_MOUNTPOINT="/dev/vda"
+    fi
   fi
-fi
+  readonly __disk_io_fifo=$__TEMP_DIR/disk_io
+  mkfifo $__disk_io_fifo
+  __disk_io_bgproc &
+}
 
 if is_osx; then
   __disk_io_bgproc () {
@@ -20,19 +25,14 @@ else
   }
 fi
 
-__disk_io_fifo=$__TEMP_DIR/disk_io
-
-init () {
-  __disk_io_bgproc &
-  mkfifo $__disk_io_fifo
-}
-
 collect () {
   report $(cat $__disk_io_fifo)
 }
 
 terminate () {
-  rm $__disk_io_fifo
+  if [ ! -z $__disk_io_fifo ] && [ -f $__disk_io_fifo ]; then
+    rm $__disk_io_fifo
+  fi
 }
 
 docs () {

metrics/disk_usage.sh

@@ -1,12 +1,14 @@
 #!/bin/sh
 
-if [ -z $DISK_USAGE_MOUNTPOINT ]; then
-  if is_osx; then
-    DISK_USAGE_MOUNTPOINT="/dev/disk1"
-  else
-    DISK_USAGE_MOUNTPOINT="/dev/vda"
+init () {
+  if [ -z $DISK_USAGE_MOUNTPOINT ]; then
+    if is_osx; then
+      DISK_USAGE_MOUNTPOINT="/dev/disk1"
+    else
+      DISK_USAGE_MOUNTPOINT="/dev/vda"
+    fi
   fi
-fi
+}
 
 collect () {
   report $(df | awk -v disk_regexp="^$DISK_USAGE_MOUNTPOINT" \

metrics/memory.sh

@@ -1,7 +1,9 @@
 #!/bin/sh
 
 if is_osx; then
-  declare -r __memory_os_memsize=$(sysctl -n hw.memsize)
+  init () {
+    readonly __memory_os_memsize=$(sysctl -n hw.memsize)
+  }
 
   collect () {
     report $(vm_stat | awk -v total_memory=$__memory_os_memsize \

metrics/network_io.sh

@@ -1,19 +1,14 @@
 #!/bin/sh
 
-if [ -z $NETWORK_IO_INTERFACE ]; then
-  if is_osx; then
-    NETWORK_IO_INTERFACE="en0"
-  else
-    NETWORK_IO_INTERFACE="eth0"
+init () {
+  if [ -z $NETWORK_IO_INTERFACE ]; then
+    if is_osx; then
+      NETWORK_IO_INTERFACE="en0"
+    else
+      NETWORK_IO_INTERFACE="eth0"
+    fi
   fi
-fi
-
-declare -r __network_io_divisor=$[$INTERVAL * 1024]
-__network_io_sample=(0 0)
-
-__network_io_calc_kBps() {
-  echo $1 $2 | awk -v divisor=$__network_io_divisor \
-                '{printf "%.2f", ($1 - $2) / divisor}'
+  readonly __network_io_divisor=$[$INTERVAL * 1024]
 }
 
 if is_osx; then
@@ -28,9 +23,14 @@ else
   }
 fi
 
+__network_io_calc_kBps() {
+  echo $1 $2 | awk -v divisor=$__network_io_divisor \
+                '{printf "%.2f", ($1 - $2) / divisor}'
+}
+
 collect () {
   local sample=( $(__network_io_collect) )
-  if [ ${__network_io_sample[0]} -ne 0 ]; then
+  if [ ! -z $__network_io_sample ]; then
     report "in" $(__network_io_calc_kBps ${sample[0]} ${__network_io_sample[0]})
     report "out" $(__network_io_calc_kBps ${sample[1]} ${__network_io_sample[1]})
   fi

metrics/ping.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+collect () {
+  report 1
+}
+
+docs () {
+  echo "Send a simple ping in form of an integer '1'."
+}