Have a collection fetching cache like we had for etesync v1.

This is there because we usually sync all of the adapters in tandem and
we were fetching all of the collections multiple times because of it.

app/src/main/java/com/etesync/syncadapter/syncadapter/SyncAdapterService.kt

@@ -30,7 +30,6 @@ import com.etesync.syncadapter.*
 import com.etesync.journalmanager.Crypto
 import com.etesync.journalmanager.Exceptions
 import com.etesync.journalmanager.JournalManager
-import com.etesync.syncadapter.*
 import com.etesync.syncadapter.log.Logger
 import com.etesync.syncadapter.model.CollectionInfo
 import com.etesync.syncadapter.model.JournalEntity
@@ -247,6 +246,14 @@ abstract class SyncAdapterService : Service() {
 
                 val etebaseLocalCache = EtebaseLocalCache.getInstance(context, account.name)
                 synchronized(etebaseLocalCache) {
+                    val cacheAge = 5 * 1000 // 5 seconds - it's just a hack for burst fetching
+                    val now = System.currentTimeMillis()
+                    val lastCollectionsFetch = collectionLastFetchMap[account.name] ?: 0
+
+                    if (abs(now - lastCollectionsFetch) <= cacheAge) {
+                        return@synchronized
+                    }
+
                     val etebase = EtebaseLocalCache.getEtebase(context, httpClient.okHttpClient, settings)
                     val colMgr = etebase.collectionManager
                     var stoken = etebaseLocalCache.loadStoken()
@@ -265,6 +272,7 @@ abstract class SyncAdapterService : Service() {
                         done = colList.isDone
                         etebaseLocalCache.saveStoken(stoken!!)
                     }
+                    collectionLastFetchMap[account.name] = now
                 }
 
                 httpClient.close()
@@ -308,5 +316,6 @@ abstract class SyncAdapterService : Service() {
 
     companion object {
         val journalFetcher = CachedJournalFetcher()
+        var collectionLastFetchMap = HashMap<String, Long>()
     }
 }