Log statistics about the SDSKeyValueStore on internal app launch

(without blocking launch, of course)

This should help us identify which SDSKeyValueStore collections might
be better promoted to full tables.

SignalMessaging/environment/AppSetup.m

@@ -235,6 +235,11 @@ NS_ASSUME_NONNULL_BEGIN
                         backgroundTask = nil;
                     }];
                 });
+
+                // Do this after we've let the main thread know that storage setup is complete.
+                if (SSKDebugFlags.internalLogging) {
+                    [SDSKeyValueStore logCollectionStatistics];
+                }
             });
         };
 

SignalServiceKit/src/Storage/Database/SDSKeyValueStore.swift

@@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2021 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2022 Open Whisper Systems. All rights reserved.
 //
 
 import Foundation
@@ -63,6 +63,29 @@ public class SDSKeyValueStore: NSObject {
         try statement.execute()
     }
 
+    @objc
+    public class func logCollectionStatistics() {
+        Logger.info("SDSKeyValueStore statistics:")
+        databaseStorage.read { transaction in
+            do {
+                let sql = """
+                    SELECT \(collectionColumn.columnName), COUNT(*)
+                    FROM \(table.tableName)
+                    GROUP BY \(collectionColumn.columnName)
+                    ORDER BY COUNT(*) DESC
+                    """
+                let cursor = try Row.fetchCursor(transaction.unwrapGrdbRead.database, sql: sql)
+                while let row = try cursor.next() {
+                    let collection: String = row[0]
+                    let count: UInt = row[1]
+                    Logger.info("- \(collection): \(count) items")
+                }
+            } catch {
+                Logger.error("\(error)")
+            }
+        }
+    }
+
     // MARK: Class Helpers
 
     @objc