add cached eval

- fixes #27
- related #15
- related #5

Author: casperdcl

scripts/cpu_percentage.sh

@@ -12,22 +12,22 @@ print_cpu_percentage() {
   if command_exists "iostat"; then
 
     if is_linux_iostat; then
-      iostat -c 1 2 | sed '/^\s*$/d' | tail -n 1 | awk -v format="$cpu_percentage_format" '{usage=100-$NF} END {printf(format, usage)}' | sed 's/,/./'
+      cached_eval iostat -c 1 2 | sed '/^\s*$/d' | tail -n 1 | awk -v format="$cpu_percentage_format" '{usage=100-$NF} END {printf(format, usage)}' | sed 's/,/./'
     elif is_osx; then
-      iostat -c 2 disk0 | sed '/^\s*$/d' | tail -n 1 | awk -v format="$cpu_percentage_format" '{usage=100-$6} END {printf(format, usage)}' | sed 's/,/./'
+      cached_eval iostat -c 2 disk0 | sed '/^\s*$/d' | tail -n 1 | awk -v format="$cpu_percentage_format" '{usage=100-$6} END {printf(format, usage)}' | sed 's/,/./'
     elif is_freebsd || is_openbsd; then
-      iostat -c 2 | sed '/^\s*$/d' | tail -n 1 | awk -v format="$cpu_percentage_format" '{usage=100-$NF} END {printf(format, usage)}' | sed 's/,/./'
+      cached_eval iostat -c 2 | sed '/^\s*$/d' | tail -n 1 | awk -v format="$cpu_percentage_format" '{usage=100-$NF} END {printf(format, usage)}' | sed 's/,/./'
     else
       echo "Unknown iostat version please create an issue"
     fi
   elif command_exists "sar"; then
-    sar -u 1 1 | sed '/^\s*$/d' | tail -n 1 | awk -v format="$cpu_percentage_format" '{usage=100-$NF} END {printf(format, usage)}' | sed 's/,/./'
+    cached_eval sar -u 1 1 | sed '/^\s*$/d' | tail -n 1 | awk -v format="$cpu_percentage_format" '{usage=100-$NF} END {printf(format, usage)}' | sed 's/,/./'
   else
     if is_cygwin; then
-      usage="$(WMIC cpu get LoadPercentage | grep -Eo '^[0-9]+')"
+      usage="$(cached_eval WMIC cpu get LoadPercentage | grep -Eo '^[0-9]+')"
       printf "$cpu_percentage_format" "$usage"
     else
-      load=`ps -aux | awk '{print $3}' | tail -n+2 | awk '{s+=$1} END {print s}'`
+      load=`cached_eval ps -aux | awk '{print $3}' | tail -n+2 | awk '{s+=$1} END {print s}'`
       cpus=$(cpus_number)
       echo "$load $cpus" | awk -v format="$cpu_percentage_format" '{printf format, $1/$2}'
     fi

scripts/gpu_percentage.sh

@@ -10,9 +10,9 @@ print_gpu_percentage() {
   gpu_percentage_format=$(get_tmux_option "@gpu_percentage_format" "$gpu_percentage_format")
 
   if command_exists "nvidia-smi"; then
-    loads=$(nvidia-smi)
+    loads=$(cached_eval nvidia-smi)
   elif command_exists "cuda-smi"; then
-    loads=$(cuda-smi)
+    loads=$(cached_eval cuda-smi)
   else
     echo "No GPU"
     return

scripts/gram_percentage.sh

@@ -10,9 +10,9 @@ print_gram_percentage() {
   gram_percentage_format=$(get_tmux_option "@gram_percentage_format" "$gram_percentage_format")
 
   if command_exists "nvidia-smi"; then
-    loads=$(nvidia-smi | sed -nr 's/.*\s([0-9]+)MiB\s*\/\s*([0-9]+)MiB.*/\1 \2/p')
+    loads=$(cached_eval nvidia-smi | sed -nr 's/.*\s([0-9]+)MiB\s*\/\s*([0-9]+)MiB.*/\1 \2/p')
   elif command_exists "cuda-smi"; then
-    loads=$(cuda-smi | sed -nr 's/.*\s([0-9.]+) of ([0-9.]+) MB.*/\1 \2/p' | awk '{print $2-$1" "$2}')
+    loads=$(cached_eval cuda-smi | sed -nr 's/.*\s([0-9.]+) of ([0-9.]+) MB.*/\1 \2/p' | awk '{print $2-$1" "$2}')
   else
     echo "No GPU"
     return

scripts/helpers.sh

@@ -62,3 +62,44 @@ command_exists() {
   local command="$1"
   command -v "$command" &> /dev/null
 }
+
+get_tmp_dir() {
+  echo "${TMPDIR:-/tmp}/tmux-$EUID-cpu"
+}
+
+get_time() {
+  date +%s
+}
+
+get_cache_val(){
+  local key="$1"
+  local timeout="${2:-1}"  # default 1 second
+  local cache="$(get_tmp_dir)/$key"
+  if [ -f "$cache" ]; then
+    awk -v cache="$(head -n1 "$cache")" -v timeout=$timeout -v now=$(get_time) \
+      'BEGIN {if (now - timeout < cache) exit 0; exit 1}' \
+      && tail -n+2 "$cache"
+  fi
+}
+
+put_cache_val(){
+  local key="$1"
+  local val="${@:2}"
+  local tmpdir="$(get_tmp_dir)"
+  [ ! -d "$tmpdir" ] && mkdir -p "$tmpdir" && chmod 0700 "$tmpdir"
+  echo "$(get_time)" > "$tmpdir/$key"
+  echo -n "$val" >> "$tmpdir/$key"
+  echo -n "$val"
+}
+
+cached_eval(){
+  local timeout=2  # seconds after which cache is invalidated
+  local command="$2"
+  local key="$(basename "$command")"
+  local val="$(get_cache_val "$key" "$timeout")"
+  if [ -z "$val" ]; then
+    put_cache_val "$key" "$($command "${@:3}")"
+  else
+    echo -n "$val"
+  fi
+}

scripts/ram_percentage.sh

@@ -17,10 +17,10 @@ print_ram_percentage() {
   ram_percentage_format=$(get_tmux_option "@ram_percentage_format" "$ram_percentage_format")
 
   if command_exists "free"; then
-    free | awk -v format="$ram_percentage_format" '$1 ~ /Mem/ {printf(format, 100*$3/$2)}'
+    cached_eval free | awk -v format="$ram_percentage_format" '$1 ~ /Mem/ {printf(format, 100*$3/$2)}'
   elif command_exists "vm_stat"; then
     # page size of 4096 bytes
-    stats="$(vm_stat)"
+    stats="$(cached_eval vm_stat)"
 
     used_and_cached=$(echo "$stats" \
       | grep -E "(Pages active|Pages inactive|Pages speculative|Pages wired down|Pages occupied by compressor)" \