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README.md

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+# pool.sh a simple processes pool management
+
+**What is pool.sh ?** pool.sh allows you to create simple pools of processes. This is usefull to run several process in parallel such as simulations. It is design to be used in bash scripts.
+
+**How it works ?**
+- Create a pool with `./pool.sh create <poolname> <capacity>`
+- Launch a process in a pool with `./pool.sh run <poolname> <command>` which return the process id `<procid>` If the pool `<poolname>` is full (number of processes equals to `<capacity>`) pool.sh will wait until room has been made in the pool to run `<command>`.
+- Get the output of a process with `./pool.sh cat <poolname> <procid>`
+- Wait until all the processes are completed with `./pool.sh wait <poolname>` 
+- Remove a pool with `./pool.sh remove <poolname>` if there is still processes running this call will fail.
+- Force the removal of a pool with `./pool.sh remove-force <poolname>` all running processes will be killed and the pool will be deleted
+- Additional properties can be attach to processes with `./pool.sh setp <poolname> <procid> <propname> <propvalue>` Defaults properties are `<cmd>`,`<procpid>`,`<startat>`.
+- Properties can be retrieve with `./pool.sh getp <poolname> <procid> <propname>`
+- Finally, all the processes output file can be retrieve with `./pool.sh ls <poolname>`
+
+**Finale quote:** No checks are performed on the pool.sh arguments. Be sure to use the right ones.

pool.sh

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+#!/usr/bin/env bash
+set -e
+
+# Fetch arguments
+CMD=$1
+POOL_ID=$2
+shift 2
+PROC_CMD=$@
+
+# Config: feel free to change at your own risks
+tmpdir=/tmp
+pool_format="pool_${POOL_ID}"
+pool="${tmpdir}/${pool_format}/"
+pool_status="${pool}/status"
+REFRESH_EVERY=1
+
+abort() {
+    echo $@
+    exit 1
+}
+
+write_status() {
+    echo "maxproc=${maxproc}" > "$pool_status"
+    echo "nproc=${nproc}" >> "$pool_status"
+    echo "procs=\"${procs}\"" >> "$pool_status"
+    echo "lastprocid=$lastprocid" >> "$pool_status"
+}
+
+write_process() {
+    file="${pool}/proc_${procid}"
+    echo cmd=\"${PROC_CMD}\" > "$file"
+    echo "procpid=${procpid}" >> "$file"
+    echo "procid=${procid}" >> "$file"
+    echo "startat=${startat}" >> "$file"
+}
+
+setp() {
+    file="${pool}/proc_${procid}"
+    echo $1=$2 >> "$file"
+}
+
+getp() {
+    file="${pool}/proc_${procid}"
+    source "$file"
+    echo "${!1}"
+}
+
+
+create() {
+    [ -d "$pool" ] && abort "Pool \"$pool\" already exists"
+    mkdir -p "$pool"
+    # Write pool status
+    maxproc=$1
+    nproc=0
+    procs=""
+    lastprocid=0
+    write_status
+}
+
+remove() {
+    refresh
+    [ $nproc -gt 0 ] && abort "Processes are still running in the pool!"
+    rm -rf "$pool"
+}
+
+refresh() {
+    source "$pool_status"
+    procs_new=""
+    for proc in $procs
+    do
+        if kill -0 $proc &>/dev/null
+        then
+            [ -z "$procs_new" ] && procs_new="$proc" || procs_new="$procs_new $proc"
+        fi
+    done
+    procs=$procs_new
+    nproc=$(echo "$procs"|wc -w)
+    write_status
+}
+
+run() {
+    refresh
+    while [ $nproc -ge $maxproc ]
+    do
+        sleep $REFRESH_EVERY
+        refresh
+    done
+    nproc=$(( nproc + 1 ))
+    procid=$(( lastprocid + 1 ))
+    lastprocid=$procid
+    startat=$(date +"%s")
+    $PROC_CMD > "$pool/out_$procid" &
+    procpid=$!
+    [ -z "$procs" ] && procs="$procpid" || procs="$procs $procpid"
+    write_status
+    write_process
+    echo $procid
+}
+
+cat_output() {
+    file="${pool}/out_${procid}"
+    cat "$file"
+}
+
+wait_pool() {
+    refresh
+    while [ $nproc -gt 0 ]
+    do
+        sleep $REFRESH_EVERY
+        refresh
+    done
+}
+
+list_output() {
+    refresh
+    find "${pool}" -name "out_*"
+}
+
+remove_force() {
+    refresh
+    for proc in $procs
+    do
+        kill -9 $proc
+    done
+    rm -rf "$pool"    
+}
+
+# Ensure pool exists
+[ ! "$CMD" == "create" ] && [ ! -d "$pool" ] && abort "Pool $POOL_ID not found"
+
+# Launch command
+case "$CMD" in
+    "create")
+        create $1
+        ;;
+    "remove")
+        remove
+        ;;
+    "run")
+        run
+        ;;
+    "cat")
+        procid=$1
+        refresh
+        [ $procid -gt $lastprocid ] && abort "Processus $procid not found"
+        cat_output
+        ;;
+    "ls")
+        list_output
+        ;;
+    "wait")
+        wait_pool
+        ;;
+    "remove-force")
+        remove_force
+        ;;
+    "setp")
+        procid=$1
+        setp $2 $3
+        ;;
+    "getp")
+        procid=$1
+        getp $2
+        ;;
+    *)
+        abort "Command $CMD unknown"
+esac