Add sequence diagrams to dynamic hedging

App-vNext · Oct 19, 2023 · e54623c · e54623c
1 parent c8dbe1a
commit e54623c
Showing 1 changed file with 97 additions and 1 deletion.
diff --git a/docs/strategies/hedging.md b/docs/strategies/hedging.md
@@ -176,7 +176,7 @@ sequenceDiagram
 
     H->>+HUC: Invokes (R1)
     HUC-->>HUC: Processes R1
-    HUC->>-H: Fails
+    HUC->>-H: Fails (R1)
 
     H->>+HUC: Invokes (R2)
     HUC-->>HUC: Processes R2
@@ -337,6 +337,102 @@ With this configuration, the hedging strategy:
 - Initiates a maximum of `4` executions. This includes initial action and an additional 3 attempts.
 - Allows the first two executions to proceed in parallel, while the third and fourth executions follow the fallback mode.
 
+#### Dynamic: happy path sequence diagram
+
+The hedging strategy triggers and switches between modes due to the usage of `DelayGenerator`. It succeeds because the last request succeeds.
+
+```mermaid
+sequenceDiagram
+    actor C as Caller
+    participant P as Pipeline
+    participant H as Hedging
+    participant DG as DelayGenerator
+    participant HUC as HedgedUserCallback
+
+    C->>P: Calls ExecuteAsync
+    P->>H: Calls ExecuteCore
+    activate H
+
+    Note over H: Parallel mode
+    par
+    H -> DG: Gets delay
+    H->>HUC: Invokes (R1)
+    activate HUC
+    and
+    H -> DG: Gets delay
+    H->>+HUC: Invokes (R2)
+    end
+
+    HUC-->>HUC: Processes R1
+    HUC-->>HUC: Processes R2
+    HUC->>-H: Fails (R2)
+    HUC->>-H: Fails (R1)
+
+    Note over H: Fallback mode
+
+    H -> DG: Gets delay
+    H->>+HUC: Invokes (R3)
+    HUC-->>HUC: Processes R3
+    HUC->>-H: Fails (R3)
+
+    H -> DG: Gets delay
+    H->>+HUC: Invokes (R4)
+    HUC-->>HUC: Processes R4
+    HUC->>-H: Returns result (R4)
+
+    deactivate H
+    H->>P: Returns result (R4)
+    P->>C: Returns result (R4)
+```
+
+#### Dynamic: unhappy path sequence diagram
+
+The hedging strategy triggers and switches between modes due to the usage of `DelayGenerator`. It fails because all requests fail.
+
+```mermaid
+sequenceDiagram
+    actor C as Caller
+    participant P as Pipeline
+    participant H as Hedging
+    participant DG as DelayGenerator
+    participant HUC as HedgedUserCallback
+
+    C->>P: Calls ExecuteAsync
+    P->>H: Calls ExecuteCore
+    activate H
+
+    Note over H: Parallel mode
+    par
+    H -> DG: Gets delay
+    H->>HUC: Invokes (R1)
+    activate HUC
+    and
+    H -> DG: Gets delay
+    H->>+HUC: Invokes (R2)
+    end
+
+    HUC-->>HUC: Processes R1
+    HUC-->>HUC: Processes R2
+    HUC->>-H: Fails (R2)
+    HUC->>-H: Fails (R1)
+
+    Note over H: Fallback mode
+
+    H -> DG: Gets delay
+    H->>+HUC: Invokes (R3)
+    HUC-->>HUC: Processes R3
+    HUC->>-H: Fails (R3)
+
+    H -> DG: Gets delay
+    H->>+HUC: Invokes (R4)
+    HUC-->>HUC: Processes R4
+    HUC->>-H: Fails (R4)
+
+    deactivate H
+    H->>P: Propagates failure (R3)
+    P->>C: Propagates failure (R3)
+```
+
 ## Action generator
 
 The hedging options include an `ActionGenerator` property, allowing you to customize the actions executed during hedging. By default, the `ActionGenerator` returns the original callback passed to the strategy. The original callback also includes any logic introduced by subsequent resilience strategies. For more advanced scenarios, the `ActionGenerator` can be used to return entirely new hedged actions, as demonstrated in the example below: