Fixed flush policy over-flush potential; Added example policy aggregator. (#362)

Author: bsneed

Examples/tasks/UncleFlushPolicy.swift

@@ -0,0 +1,60 @@
+//
+//  UncleFlushPolicy.swift
+//  Segment
+//
+//  Created by Brandon Sneed on 9/17/24.
+//
+
+import Foundation
+
+public class UncleFlushPolicy: FlushPolicy {
+    public weak var analytics: Analytics?
+    internal var basePolicies: [FlushPolicy] = [CountBasedFlushPolicy(), IntervalBasedFlushPolicy(), /* .. add your own here .. */]
+    
+    public init() {
+        /*
+         or add your own here ...
+         
+         ```
+         self.basePolicies.append(MyCrazyUnclesOtherPolicy(onThanksgiving: true)
+         ```
+         */
+    }
+    
+    private func shouldWeREALLYFlush() -> Bool {
+        // do some meaningful calculation or check here.
+        // Ol Unc's was right i guess since we're gonna do what he says.
+        return true
+    }
+    
+    public func configure(analytics: Analytics) {
+        self.analytics = analytics
+        basePolicies.forEach { $0.configure(analytics: analytics) }
+    }
+    
+    public func shouldFlush() -> Bool {
+        guard let a = analytics else {
+            return false
+        }
+        
+        var shouldFlush = false
+        for policy in basePolicies {
+            shouldFlush = policy.shouldFlush() || shouldFlush
+        }
+        
+        if shouldFlush {
+            // ask the know it all ...
+            shouldFlush = shouldWeREALLYFlush()
+        }
+        
+        return shouldFlush
+    }
+    
+    public func updateState(event: RawEvent) {
+        basePolicies.forEach { $0.updateState(event: event) }
+    }
+    
+    public func reset() {
+        basePolicies.forEach { $0.reset() }
+    }
+}

Sources/Segment/Analytics.swift

@@ -99,14 +99,35 @@ public class Analytics {
 
         _ = timeline.process(incomingEvent: event, enrichments: enrichments)
 
-        let flushPolicies = configuration.values.flushPolicies
+        /*let flushPolicies = configuration.values.flushPolicies
         for policy in flushPolicies {
             policy.updateState(event: event)
 
             if (policy.shouldFlush() == true) {
                 flush()
                 policy.reset()
             }
+        }*/
+        
+        let flushPolicies = configuration.values.flushPolicies
+        
+        var shouldFlush = false
+        // if any policy says to flush, make note of that
+        for policy in flushPolicies {
+            policy.updateState(event: event)
+            if policy.shouldFlush() {
+                shouldFlush = true
+                // we don't need to updateState on any others since we're gonna reset it below.
+                break
+            }
+        }
+        // if we were told to flush do it.
+        if shouldFlush {
+            // reset all the policies if one decided to flush.
+            flushPolicies.forEach {
+                $0.reset()
+            }
+            flush()
         }
     }