Leo scripts to manage History Tracer plugin daemon

console-log.md

An edited excerpt from the console which started Leo

don't forget to launch leo-ver-serv!!!
==== @int history-tracer-port=8088 ====
Looking for 'leo-ver-serv' processes...
   PID   Name                   Status    
  3815   leo-ver-serv           sleeping  
========================================

This is just after Leo startup. The first thing I did was run the list services script. Sleeping is normal status for the server.

But let's pretend we don't know this and we attempt to start the service:

Running: leo-ver-serv /home/matt/.leo/.leoRecentFiles.txt 8088
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 98, kind: AddrInUse, message: "Address already in use" }', src/libcore/result.rs:1188:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

Uhoh. List the services again:

==== @int history-tracer-port=8088 ====
Looking for 'leo-ver-serv' processes...
   PID   Name                   Status    
  3815   leo-ver-serv           sleeping  
  5335   leo-ver-serv           zombie    
========================================

So we still have our first real servivce, and a new zombie because of the crash above.

Let's try and shut them down gracefully, and then list again:

process psutil.Process(pid=5335, status='terminated') terminated with exit code 101
process psutil.Process(pid=3815, status='terminated') terminated with exit code None
==== @int history-tracer-port=8088 ====
Looking for 'leo-ver-serv' processes...
   PID   Name                   Status    
========================================

The double bar immediately following 'Status' indicates no services found. In the next version we should have it say None and remove guesswork.

leo-ver-serv-list.py

@language python
g.es_print("====", c.p.h, "====")
g.es_print("Looking for 'leo-ver-serv' processes...")
import psutil

process = [proc for proc in psutil.process_iter() if proc.name() == "leo-ver-serv"]
# g.es_print(f"Process: {process}") # debug

g.es_print("{:>6}   {:<20}   {:<10}".format('PID', 'Name', 'Status'))

for p in process:
    g.es_print("{:>6}   {:<20}   {:<10}".format(p.pid, p.name(), p.status()))
    # g.es_print(p.open_files()) # raises AccessDenied if not run as root
    #g.es_print(p.children()) # not needed, always empty (so far)
  
g.es_print("=" * 40)

leo-ver-serv-start.py

@language python
'''Start 'leo-ver-serv' for History Tracer plugin'''
import os
watchfiles = os.path.join(g.computeHomeDir(), '.leo/.leoRecentFiles.txt')

if os.path.exists(watchfiles):
    g.es_print(f"Running: leo-ver-serv {watchfiles} 8088")
    os.spawnlp(os.P_NOWAIT, 'leo-ver-serv', watchfiles, '8088')
else:
    g.es_print(f"Couldn't find {watchfiles}")

'''TODO: see if can use psutils instead for better communication/monitoring
https://psutil.readthedocs.io/en/latest/#popen-class'''

leo-ver-serv-stop.py

@language python
'''Gracefully shutdown any processes named 'leo-ver-serv'
Adapted from https://psutil.readthedocs.io/en/latest/#psutil.wait_procs
'''
import psutil

def on_terminate(proc):
    print("process {} terminated with exit code {}".format(proc, proc.returncode))

procs = [proc for proc in psutil.process_iter() if proc.name() == "leo-ver-serv"]

for p in procs:
    p.terminate()
gone, alive = psutil.wait_procs(procs, timeout=3, callback=on_terminate)
for p in alive:
    p.kill()