Fix review comments on IndexedPriorityQueue

- Clear vacated heap slots to default in DequeueFromHeap and TryRemove
  to prevent retaining references to removed elements
- Ensure TryRemove always runs shrink check even when removing last element
- Add XML doc comment to Exists method

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: hamdaankhalidmsft

Garnet.scapy/README.md

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+# Garnet Accept Loop — Scapy TCP Attack Tests
+
+Standalone Python test suite that uses [scapy](https://scapy.net/) to craft raw TCP packets
+simulating malicious handshake disruptions against a running Garnet server.
+
+These tests exercise accept error handling code paths that **cannot be reached** via standard
+socket APIs on Windows (which blocks raw TCP sockets since XP SP2).
+
+## Prerequisites
+
+- Python 3.8+
+- [Npcap](https://npcap.com/) (Windows) or root access (Linux)
+- **Run as Administrator** (Windows) or root (Linux) for raw socket access
+
+## Install
+
+```bash
+pip install scapy
+```
+
+## Usage
+
+Start a Garnet server first, then run the attacks against it:
+
+```bash
+# Run all tests against local Garnet server (default port 33278)
+python test_accept_loop_attacks.py
+
+# Specify host/port
+python test_accept_loop_attacks.py --host 127.0.0.1 --port 6379
+
+# Run a specific test
+python test_accept_loop_attacks.py --test rst_before_ack
+
+# More iterations
+python test_accept_loop_attacks.py --count 200
+
+# List available tests
+python test_accept_loop_attacks.py --list
+```
+
+## Tests
+
+| Test | Attack | Expected SocketError |
+|------|--------|---------------------|
+| `rst_before_ack` | SYN → SYN-ACK → **RST** (instead of ACK) | `ConnectionReset` |
+| `rst_after_ack` | SYN → SYN-ACK → ACK → **RST** (immediately) | `ConnectionReset` |
+| `fin_before_ack` | SYN → SYN-ACK → **FIN** (instead of ACK) | `ConnectionAborted` |
+| `syn_then_silence` | SYN → SYN-ACK → *(silence)* | `TimedOut` |
+| `malformed_syn_options` | SYN with zero window, tiny MSS | Various |
+
+Each test sends the attack packets, then verifies the server still accepts
+new connections and responds to PING. If the accept loop is broken, the
+post-test PING will fail.
+
+## What this tests
+
+The tiered error handling in `GarnetServerTcp.HandleAcceptError`:
+
+- **Tier 3 (transient):** `ConnectionReset`, `ConnectionAborted`, `TimedOut` — log and continue
+- **Tier 2 (resource pressure):** `TooManyOpenSockets`, etc. — backoff and retry
+- **Tier 1 (fatal):** `OperationAborted` (shutdown) — stop loop; `NotSocket` etc. — crash process

Garnet.scapy/requirements.txt

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+scapy>=2.5.0