Feature/event injection runtime (#20)

* Events injection for edges part 1

* Logic + docs for the event injection to simulate a server down

* Added pydantic validation + unit + int tests for eventinjection

* added exaple for event inj yaml + builder added int tests

* improved server model + system tests for eventinjection

* ruff small fix

Author: GioeleB00

CHANGELOG.MD

@@ -0,0 +1,106 @@
+
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
+
+## \[Unreleased]
+
+### Added
+
+* **Event Injection input schema** (merged on `develop`):
+
+  * Declarative events with `start` / `end` markers (server **down/up**, network **spike start/end**).
+  * Strong validation (Pydantic):
+
+    * `event_id` uniqueness.
+    * `target_id` must exist (server or edge).
+    * Start/end times within the simulation horizon and well-ordered.
+    * Kind ↔ target compatibility (server events must target servers, network events must target edges).
+    * Safety guard: **never all servers down simultaneously**.
+* Documentation comments and examples for authoring event windows in YAML.
+
+### In Progress
+
+* **Runtime Event Scheduler**: SimPy process to apply events at scheduled times.
+* **Edge spike handling (phase 1)**: deterministic latency **offsets** during spike windows (no changes to base distributions yet).
+
+---
+
+## \[0.1.0a2] – 2025-08-17
+
+### Fixed
+
+* **Quickstart YAML in README**: corrected field to ensure a smooth first run for new users.
+
+### Notes
+
+* Minor docs polish only; no runtime changes.
+
+---
+
+## \[0.1.0a1] – 2025-08-17
+
+### Changed
+
+* Repository aligned with the **PyPI 0.1.0a1** build.
+* Packaging metadata tidy-up in `pyproject.toml`.
+
+### CI
+
+* Main workflow now also triggers on **push** to `main`.
+
+### Notes
+
+* No functional/runtime changes.
+
+---
+
+## \[v0.1.0-alpha] – 2025-08-17
+
+**First public alpha** of AsyncFlow — a SimPy-based, **event-loop-aware** simulator for async distributed systems.
+
+### Highlights
+
+* **Event-loop model** per server: explicit **CPU** (blocking), **I/O waits** (non-blocking), **RAM** residency.
+* **Topology graph**: generator → client → (LB, optional) → servers; multi-server via **round-robin**; **stochastic network latency** and optional dropouts.
+* **Workload**: stochastic traffic via simple RV configs (Poisson defaults).
+
+### Metrics & Analyzer
+
+* **Event metrics**: `RqsClock` (end-to-end latency).
+* **Sampled metrics**: `ready_queue_len`, `event_loop_io_sleep`, `ram_in_use`, `edge_concurrent_connection`.
+* **Analyzer API** (`ResultsAnalyzer`):
+
+  * `get_latency_stats()`, `get_throughput_series()`
+  * Plots: `plot_latency_distribution()`, `plot_throughput()`
+  * Per-server: `plot_single_server_ready_queue()`, `plot_single_server_io_queue()`, `plot_single_server_ram()`
+  * Compact dashboards.
+
+### Examples
+
+* YAML quickstart (single server).
+* Pythonic builder:
+
+  * Single server.
+  * **Load balancer + two servers** example with saved figures.
+
+### Tooling & CI
+
+* One-shot setup scripts (`dev_setup`, `quality_check`, `run_tests`, `run_sys_tests`) for Linux/macOS/Windows.
+* GitHub Actions: Ruff + MyPy + Pytest; **system tests gate merges** into `main`.
+
+### Compatibility
+
+* **Python 3.12+** (Linux/macOS/Windows).
+* Install from PyPI: `pip install asyncflow-sim`.
+
+### Known Limitations (alpha)
+
+* Network: latency + optional drops (no bandwidth/payload/TCP yet).
+* Single event loop per server (no multi-process/node).
+* Linear endpoint pipelines (no branching/fan-out inside endpoints).
+* Stationary workload; very short spikes may be missed if `sample_period_s` is large.
+
+

docs/internals/edges-events-injection.md

@@ -0,0 +1,277 @@
+# Edge Event Injection: Architecture & Operations
+
+This document explains how **edge-level events** (e.g., deterministic latency spikes) are modeled, centralized, and injected into the simulation. It covers:
+
+* Data model (start/end markers & validation)
+* The **central event runtime** (timeline, cumulative offsets, live adapters)
+* How **SimulationRunner** wires everything
+* How **EdgeRuntime** consumes the adapters during delivery
+* Ordering, correctness guarantees, and trade-offs
+* Extension points and maintenance tips
+
+---
+
+## 1) Conceptual Model
+
+### What’s an “edge event”?
+
+An edge event is a **time-bounded effect** applied to a specific network edge (link). Today we support **latency spikes**: while the event is active, the edge’s transit time is increased by a fixed offset (`spike_s`) in seconds.
+
+### Event markers
+
+Events are defined with two **markers**:
+
+* `Start` (`kind` in `{NETWORK_SPIKE_START, SERVER_DOWN}`)
+* `End` (`kind` in `{NETWORK_SPIKE_END, SERVER_UP}`)
+
+Validation guarantees:
+
+* **Kind pairing** is coherent (e.g., `NETWORK_SPIKE_START` ↔ `NETWORK_SPIKE_END`).
+* **Time ordering**: `t_start < t_end`.
+* For network spike events, **`spike_s` is required** and positive.
+
+> These guarantees are enforced by the Pydantic models and their `model_validator`s in the schema layer, *before* runtime.
+
+---
+
+## 2) Centralized Event Registry: `EventInjectionRuntime`
+
+`EventInjectionRuntime` centralizes all event logic and exposes **live read-only views** (adapters) to edge actors.
+
+### Responsibilities & Data
+
+* **Input**:
+
+  * `events: list[EventInjection] | None`
+  * `edges: list[Edge]`, `servers: list[Server]`, `env: simpy.Environment`
+* **Internal state**:
+
+  * `self._edges_events: dict[event_id, dict[edge_id, float]]`
+    Mapping from event → edge → spike amplitude (`spike_s`).
+    This allows multiple events per edge and distinguishes overlapping events.
+  * `self._edges_spike: dict[edge_id, float]`
+    **Cumulative** spike currently active per edge (updated at runtime).
+  * `self._edges_affected: set[edge_id]`
+    All edges that are ever impacted by at least one event.
+  * `self._edges_timeline: list[tuple[time, event_id, edge_id, mark]]`
+    Absolute timestamps (`time`) with `mark ∈ {start, end}` for **edges**.
+  * (We also construct a server timeline, reserved for future server-side effects.)
+
+> If `events` is `None` or empty, the runtime initializes to empty sets/maps and **does nothing** when started.
+
+### Build step (performed in `__init__`)
+
+1. Early return if there are no events (keeps empty adapters).
+2. Partition events by **target type** (edge vs server).
+3. For each **edge** event:
+
+   * Record `spike_s` in `self._edges_events[event_id][edge_id]`.
+   * Append `(t_start, event_id, edge_id, start)` and `(t_end, event_id, edge_id, end)` to the **edge timeline**.
+   * Add `edge_id` to `self._edges_affected`.
+4. **Sort** timelines by `(time, mark == start, event_id, edge_id)` so that at equal time, **end** is processed **before start**.
+   (Because `False < True`, `end` precedes `start`.)
+
+### Runtime step (SimPy process)
+
+The coroutine `self._assign_edges_spike()`:
+
+* Iterates the ordered timeline of **absolute** timestamps.
+* Converts absolute `t_event` to relative waits via `dt = t_event - last_t`.
+* After waiting `dt`, applies the state change:
+
+  * On **start**: `edges_spike[edge_id] += delta`
+  * On **end**:   `edges_spike[edge_id] -= delta`
+
+This gives a continuously updated, **cumulative** spike per edge, enabling **overlapping events** to stack linearly.
+
+### Public adapters (read-only views)
+
+* `edges_spike: dict[str, float]` — current cumulative spike per edge.
+* `edges_affected: set[str]` — edges that may ever be affected.
+
+These are **shared** with `EdgeRuntime` instances, so updates made by the central process are immediately visible to the edges **without any signaling or copying**.
+
+---
+
+## 3) Wiring & Lifecycle: `SimulationRunner`
+
+`SimulationRunner` orchestrates creation, wiring, and startup order.
+
+### Build phase
+
+1. Build node runtimes (request generator, client, servers, optional load-balancer).
+2. Build **edge runtimes** (`EdgeRuntime`) with their target boxes (stores).
+3. **Build events**:
+
+   * If `simulation_input.events` is empty/None → **skip** (no process, no adapters).
+   * Else:
+
+     * Construct **one** `EventInjectionRuntime`.
+     * Extract adapters: `edges_affected`, `edges_spike`.
+     * Attach these **same objects** to **every** `EdgeRuntime`.
+       (EdgeRuntime performs a membership check; harmless for unaffected edges.)
+
+> We deliberately attach adapters to all edges for simplicity. This is O(1) memory for references, and O(1) runtime per delivery (one membership + dict lookup). If desired, the runner could pass adapters **only** to affected edges—this would save a branch per delivery at the cost of more conditional wiring logic.
+
+### Start phase (order matters)
+
+* `EventInjectionRuntime.start()` — **first**
+  Ensures that the spike timeline is active before edges start delivering; the first edge transport will see the correct offset when due.
+* Start all other actors.
+* Start the metric collector (RAM / queues / connections snapshots).
+* `env.run(until=total_simulation_time)` to advance the clock.
+
+### Why this order?
+
+* Prevents race conditions where the first edge message observes stale (`0.0`) spike at time ≈ `t_start`.
+* Keeps the architecture deterministic and easy to reason about.
+
+---
+
+## 4) Edge Consumption: `EdgeRuntime`
+
+Each edge has:
+
+* `edges_affected: Container[str] | None`
+* `edges_spike: Mapping[str, float] | None`
+
+During `_deliver(state)`:
+
+1. Sample base latency from the configured RV.
+2. If adapters are present **and** `edge_id ∈ edges_affected`:
+
+   * Read `spike = edges_spike.get(edge_id, 0.0)`
+   * `effective = base_latency + spike`
+3. `yield env.timeout(effective)`
+
+No further coordination required: the **central** process updates `edges_spike` as time advances, so each delivery observes the **current** spike.
+
+---
+
+## 5) Correctness & Guarantees
+
+* **Temporal correctness**: Absolute → relative time conversion (`dt = t_event - last_t`) ensures the process applies changes at the exact timestamps. Sorting ensures **END** is processed before **START** when times coincide, so zero-length events won’t “leak” positive offset.
+* **Coherence**: Pydantic validators enforce event pairing and time ordering.
+* **Immutability**: Marker models are frozen; unknown fields are forbidden.
+* **Overlap**: Multiple events on the same edge stack linearly (`+=`/`-=`).
+
+---
+
+## 6) Performance & Trade-offs
+
+### Centralized vs Distributed
+
+* **Chosen**: one central `EventInjectionRuntime` with live adapters.
+
+  * **Pros**: simple mental model; single source of truth; O(1) read for edges; no per-edge coroutines; minimal memory traffic.
+  * **Cons**: single process to maintain (but it’s lightweight); edges branch on membership.
+
+* **Alternative A**: deliver the **full** event runtime object to each edge.
+
+  * **Cons**: wider API surface; tighter coupling; harder to evolve; edges would get capabilities they don’t need (SRP violation).
+
+* **Alternative B**: per-edge local event processes.
+
+  * **Cons**: one coroutine per edge (N processes), more scheduler overhead, duplicated logic & sorting.
+
+### Passing adapters to *all* edges vs only affected edges
+
+* **Chosen**: pass to all edges.
+
+  * **Pros**: wiring stays uniform; negligible memory; O(1) branch in `_deliver`.
+  * **Cons**: trivial per-delivery branch even for unaffected edges.
+* **Alternative**: only affected edges receive adapters.
+
+  * **Pros**: removes one branch at delivery.
+  * **Cons**: more conditional wiring, more moving parts for little gain.
+
+---
+
+## 7) Sequence Overview
+
+```
+SimulationRunner.run()
+ ├─ _build_rqs_generator()
+ ├─ _build_client()
+ ├─ _build_servers()
+ ├─ _build_load_balancer()
+ ├─ _build_edges()
+ ├─ _build_events()
+ │    └─ EventInjectionRuntime(...):
+ │         - build _edges_events, _edges_affected
+ │         - build & sort _edges_timeline
+ │
+ ├─ _start_events()
+ │    └─ start _assign_edges_spike()  (central timeline process)
+ │
+ ├─ _start_all_processes()  (edges, client, servers, etc.)
+ ├─ _start_metric_collector()
+ └─ env.run(until = T)
+```
+
+During `EdgeRuntime._deliver()`:
+
+```
+base = sample(latency_rv)
+if adapters_present and edge_id in edges_affected:
+    spike = edges_spike.get(edge_id, 0.0)
+    effective = base + spike
+else:
+    effective = base
+yield env.timeout(effective)
+```
+
+---
+
+## 8) Extensibility
+
+* **Other edge effects**: add new event kinds and store per-edge state (e.g., drop-rate bumps) in `_edges_events` and update logic in `_assign_edges_spike()`.
+* **Server outages**: server timeline is already scaffolded; add a server process to open/close resources (e.g., capacity=0 during downtime).
+* **Non-deterministic spikes**: swap `float` `spike_s` for a small sampler (callable) and apply the sampled value at each **start**, or at each **delivery** (define semantics).
+* **Per-edge filtering in runner** (micro-optimization): only wire adapters to affected edges.
+
+---
+
+## 9) Operational Notes & Best Practices
+
+* **Start order** matters: always start `EventInjectionRuntime` *before* edges.
+* **Adapters must be shared** (not copied) to preserve live updates.
+* **Keep `edges_spike` additive** (no negative values unless you introduce “negative spikes” intentionally).
+* **Time units**: seconds everywhere; keep it consistent with sampling.
+* **Validation first**: reject malformed events early (schema layer), *not* in runtime.
+
+---
+
+## 10) Glossary
+
+* **Adapter**: a minimal, read-only view (e.g., `Mapping[str, float]`, `Container[str]`) handed to edges to observe central state without owning it.
+* **Timeline**: sorted list of `(time, event_id, edge_id, mark)` where `mark ∈ {start, end}`.
+* **Spike**: deterministic latency offset to be added to the sampled base latency.
+
+---
+
+## 11) Example (end-to-end)
+
+**YAML (conceptual)**
+
+```yaml
+events:
+  - event_id: ev-spike-1
+    target_id: edge-42
+    start: { kind: NETWORK_SPIKE_START, t_start: 12.0, spike_s: 0.050 }
+    end:   { kind: NETWORK_SPIKE_END,   t_end:   18.0 }
+```
+
+**Runtime effect**
+
+* From `t ∈ [12, 18)`, `edge-42` adds **+50 ms** to its sampled latency.
+* Overlapping events stack: `edges_spike["edge-42"]` is the **sum** of active spikes.
+
+---
+
+## 12) Summary
+
+* We centralize event logic in **`EventInjectionRuntime`** and expose **live adapters** to edges.
+* Edges read **current cumulative spikes** at delivery time—**no coupling** and **no extra processes per edge**.
+* The runner keeps the flow simple and deterministic: **build → wire → start events → start actors → run**.
+* The architecture is **extensible**, **testable**, and **performant** for realistic workloads.