Request change VTODO parsing errors to be non-fatal / improve logging

[ccoenen]

I am experiencing the same problem as described in Tasks are not synchronized: DUE must not be < DTSTART.

Sadly, I have quite a few tasks, so that going over each item one by one to find the faulty one is not practical. So right now, I’m left with no working sync.

I would like to suggest two things

1. Improve logging to a point where I can easily identify the faulty task. The log output could just also dump the plain text it’s trying to parse below the stack trace. That would be immensely helpful. Other helpful Solutions would be to include the faulty timestamps if it’s easier. Basically: include anything that allows me to narrow down the faulty tasks.
2. (From the stack trace i’m not sure it falls within the domain of DAVdroid.) I do realize that DUE < DTSTART is against the specs. Warn about it all you want. But please don’t throw everything else under the bus by throwing an exception.

Steps to reproduce

• Have a VTODO on your server that has DUE < DTSTART.
• Sync
• See this message in your notification area
  
• See this log message

  SYNCHRONIZATION INFO
  Synchronization phase: 9
  Account name: ---redacted---
  Authority: org.dmfs.tasks
  
  EXCEPTION:
  java.lang.IllegalArgumentException: DUE must not be < DTSTART
  	at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:165)
  	at android.database.DatabaseUtils.readExceptionWithOperationApplicationExceptionFromParcel(DatabaseUtils.java:158)
  	at android.content.ContentProviderProxy.applyBatch(ContentProviderNative.java:520)
  	at android.content.ContentProviderClient.applyBatch(ContentProviderClient.java:418)
  	at at.bitfire.ical4android.BatchOperation.runBatch(BatchOperation.java:86)
  	at at.bitfire.ical4android.BatchOperation.commit(BatchOperation.java:58)
  	at at.bitfire.ical4android.AndroidTask.update(AndroidTask.java:237)
  	at at.bitfire.davdroid.syncadapter.TasksSyncManager.processVTodo(TasksSyncManager.java:205)
  	at at.bitfire.davdroid.syncadapter.TasksSyncManager.downloadRemote(TasksSyncManager.java:145)
  	at at.bitfire.davdroid.syncadapter.SyncManager.performSync(SyncManager.java:170)
  	at at.bitfire.davdroid.syncadapter.TasksSyncAdapterService$SyncAdapter.onPerformSync(TasksSyncAdapterService.java:78)
  	at android.content.AbstractThreadedSyncAdapter$SyncThread.run(AbstractThreadedSyncAdapter.java:272)
  
  SOFTWARE INFORMATION
  DAVdroid version: 1.3.1-ose (116) Wed Sep 21 08:17:52 GMT+02:00 2016
  Installed from: org.fdroid.fdroid
  JB Workaround installed: no
  
  CONFIGURATION
  System-wide synchronization: automatically
  Account: ---redacted---
    Address book sync. interval: x min
    Calendar     sync. interval: x min
    OpenTasks    sync. interval: x min
    WiFi only: x
    [CardDAV] Contact group method: CATEGORIES
              RFC 6868 encoding: x
    [CalDAV] Time range (past days): x
             Manage calendar colors: x
  
  SQLITE DUMP
  android_metadata
  	|  locale |
  	|  x |
  ----------
  settings
  	|  setting | value |
  	|  hint_OpenTasksNotInstalled | 0 |
  ----------
  services
  	|  _id | accountName | service | principal |
  	|  3 | ---redacted--- | carddav | ---redacted--- |
  	|  4 | ---redacted--- | caldav | ---redacted--- |
  ----------
  sqlite_sequence
  	|  name | seq |
  	|  services | 4 |
  	|  collections | 52 |
  	|  homesets | 11 |
  ----------
  homesets
  	|  _id | serviceID | url |
  	|  10 | 4 | ---redacted--- |
  	|  11 | 3 | ---redacted--- |
  ----------
  collections
  	|  _id | serviceID | url | readOnly | displayName | description | color | timezone | supportsVEVENT | supportsVTODO | sync |
  	|  44 | 4 | ---redacted--- | 1 | ---redacted--- | ---redacted--- | -54 | <null> | 1 | 1 | 0 |
  	|  45 | 4 | ---redacted--- | 0 | ---redacted--- | ---redacted--- | -6306073 | <null> | 1 | 1 | 1 |
  	|  46 | 4 | ---redacted--- | 0 | ---redacted--- | ---redacted--- | -1146130 | <null> | 1 | 1 | 1 |
  	|  47 | 4 | ---redacted--- | 0 | ---redacted--- | ---redacted--- | -16777216 | <null> | 1 | 1 | 1 |
  	|  48 | 4 | ---redacted--- | 0 | ---redacted--- | ---redacted--- | -1605516 | <null> | 1 | 1 | 1 |
  	|  49 | 4 | ---redacted--- | 0 | ---redacted--- | ---redacted--- | -8355840 | <null> | 1 | 1 | 1 |
  	|  50 | 4 | ---redacted--- | 0 | ---redacted--- | ---redacted--- | -4989844 | <null> | 1 | 1 | 1 |
  	|  51 | 4 | ---redacted--- | 1 | ---redacted--- | ---redacted--- | -32944 | <null> | 1 | 1 | 1 |
  	|  52 | 3 | ---redacted--- | 0 | ---redacted--- | ---redacted--- | <null> | <null> | <null> | <null> | 1 |
  ----------
  
  SYSTEM INFORMATION
  Android version: 6.0.1 (---redacted---)
  Device: ---redacted---