API detects of wrong/non-existing content change

[Здравко]

Hello,

I have an issue with calling /2/files/list_folder/longpoll. For whatever reason, this endpoint activates from and detects changes that are not on the observed folder, but outside it. Something that according documentation shouldn't happen, but it happens. This disturbs application workflow and significantly decrease the efficiency - instead of one or two changes tracking, lot of folders trackers start calling /2/files/list_folder/continue simultaneous - something completely meaningless.

Simplistic example with 3 folders and one file move between 2 of them reproduces the issue:

#!/bin/bash
##############################################################################
#                     Strange firing "NO event" events!?
#                     ==================================
# Save this file as "fropbox_bugtest" for instance and make it executable:
#   $ chmod a+x fropbox_bugtest
#
# Set valid access token
# (like from here - https://dropbox.github.io/dropbox-api-v2-explorer/ )
# and, at the end, just run it:
#   $ ./fropbox_bugtest
#
##############################################################################

ACCESS_TOKEN="PUT VALID ACCESS TOKEN HERE"

# Creating of 3 completely new independent empty folders:
curl https://api.dropboxapi.com/2/files/create_folder_v2 \
  --oauth2-bearer "$ACCESS_TOKEN" -H 'Content-Type: application/json' \
  -d '{"path":"/Folder1"}' > /dev/null 2> /dev/null
curl https://api.dropboxapi.com/2/files/create_folder_v2 \
  --oauth2-bearer "$ACCESS_TOKEN" -H 'Content-Type: application/json' \
  -d '{"path":"/Folder2"}' > /dev/null 2> /dev/null
curl https://api.dropboxapi.com/2/files/create_folder_v2 \
  --oauth2-bearer "$ACCESS_TOKEN" -H 'Content-Type: application/json' \
  -d '{"path":"/Folder3"}' > /dev/null 2> /dev/null

# Put a test file in the first folder:
curl https://content.dropboxapi.com/2/files/upload \
  --oauth2-bearer "$ACCESS_TOKEN" -H 'Content-Type: application/octet-stream' \
  -H 'Dropbox-API-Arg: {"path":"/Folder1/test.txt"}' \
  -d 'Hello World' > /dev/null 2> /dev/null

# Let's be observing what's going on about all folders:
observeFolder() {
  local ID
  ID=`curl https://api.dropboxapi.com/2/files/list_folder/get_latest_cursor \
    --oauth2-bearer "$ACCESS_TOKEN" -H 'Content-Type: application/json' \
    -d "{\"include_deleted\":true,\"path\":\"$1\"}" 2> /dev/null \
    | jq -r .cursor`
  echo "Observing '$1'..."
  echo "$1 result:" $'\n' `\
  curl https://notify.dropboxapi.com/2/files/list_folder/longpoll \
    -H 'Content-Type: application/json' -d "{\"cursor\":\"$ID\"}" \
    2> /dev/null` $'\n' `\
  curl https://api.dropboxapi.com/2/files/list_folder/continue \
    --oauth2-bearer "$ACCESS_TOKEN" -H 'Content-Type: application/json' \
    -d "{\"cursor\":\"$ID\"}" 2> /dev/null \
    | jq '{entries:.entries,has_more:.has_more}'` $'\n'
}

observeFolder "/Folder1" &
P1="$!"
observeFolder "/Folder2" &
P2="$!"
observeFolder "/Folder3" &
P3="$!"

# Wait for a moment to make sure the observe got started.
sleep 1

# Let's move the test file between 2 of the folders:
curl https://api.dropboxapi.com/2/files/move_v2 \
  --oauth2-bearer "$ACCESS_TOKEN" -H 'Content-Type: application/json' \
  -d '{"from_path":"/Folder1/test.txt","to_path":"/Folder2/test.txt"}' \
  > /dev/null 2> /dev/null
echo 'test.txt got moved from /Folder1 to /Folder2'

# Wait to see what's going on with observations.
wait "$P1"
wait "$P2"
wait "$P3"
echo "The test is over."

# Some cleanup:
curl https://api.dropboxapi.com/2/files/delete_batch \
  --oauth2-bearer "$ACCESS_TOKEN" -H 'Content-Type: application/json' \
  -d `jq -c '{entries:[{path:.[]}]}' <<< '["/Folder1","/Folder2","/Folder3"]'` \
  > /dev/null 2> /dev/null

In fact 2 folders out of 3, in total, get changed. What is the expected output of the above script? 🤔

It's easy it be run and... the output observed. How many {"changes":true} have to be there and {"changes":false} accordingly? 🧐 How many are they actually? Why?

Any thoughts and proposals are welcome.

Thanks in advance.

[Greg-DB]

Thanks for the detailed report. This is a known issue with the /2/files/list_folder/longpoll functionality; it currently does not restrict its change detection to the specific path set for the supplied cursor. This is open with the team, but I don't have a timeline for a resolution. I'll follow up here with any news.

[Здравко]

Thanks for clarification @Greg-DB.

Hope this will be solved soon.

ADD: Just for completeness: It's not related to path only - even when cursor points to ID, the behavior is still the same.