watchContacts.bash

#!/bin/bash

# This is a tool to control contactsd on macOS. For some reason, contactsd
# consumes a lot of CPU when running against my (large, 9,779 entry)
# addressbook. I think contactsd is responsible for synchronizing the
# addressbook in the background, but it makes my local instance of the Contacts
# app hang and burns up my battery. So I stop contactsd when I use the Contacts
# app and then restart it to allow the sync to happen. However, modern macOS
# will not allow one to disable the contactsd launch agent. System Integrity
# Protection will also not allow one to disable it. So what I really do is
# send the process a SIGSTOP signal to make it hang. Then I just restart it
# when I really want to start it.

contactsd_status=normal

while true
do

   foreground=$(osascript -e 'tell application "System Events"' -e 'set frontApp to name of first application process whose frontmost is true' -e 'end tell')

   if [ $foreground = "Contacts" ]
   then

     echo "Contacts is in the foreground."

     if [ $contactsd_status = "normal" ]
     then

       echo "Pausing contactsd."

       # Get the PID of the running contactds process
       CPID=$(launchctl list | grep com.apple.contactsd | cut -d$'\t' -f1)

       if [ $CPID != "-" ]
       then
         # Send a SIGSTOP to the process to pause it. If we kill it, launchd will
         # just restart it.
         kill -SIGSTOP $CPID

         contactsd_status=paused
       fi

     fi

   else

     echo "Contacts is not in the foreground."

     if [ $contactsd_status = "paused" ]
     then

       echo "Restarting contactsd."
       launchctl stop com.apple.contactsd && launchctl start com.apple.contactsd
       contactsd_status=normal

     fi

   fi

   sleep 1
done