This implements the periodic STATE_UPDATE mechanism described in DESIGN.txt
lines 80-99, where the metadata server periodically sends synchronization
messages to chunk servers.
Changes:
1. Added timing fields to ChunkServerPeer:
- last_sync_time: tracks when STATE_UPDATE was last sent
- last_response_time: tracks when chunk server last responded
2. Added health check configuration constants (config.h):
- HEALTH_CHECK_INTERVAL: 30 seconds between STATE_UPDATE messages
- HEALTH_CHECK_TIMEOUT: 90 seconds before marking server as unhealthy
3. Implemented send_state_update() function:
- Serializes and sends add_list and rem_list to chunk servers
- Updates last_sync_time when messages are sent
4. Added message handlers for chunk server responses:
- process_chunk_server_state_update_success(): merges add_list into old_list,
clears pending lists, updates last_response_time
- process_chunk_server_state_update_error(): handles missing chunks,
updates last_response_time, logs errors
5. Implemented periodic timer logic in metadata_server_step():
- Calculates when next STATE_UPDATE should be sent to each chunk server
- Sends updates when HEALTH_CHECK_INTERVAL has elapsed
- Logs warnings when chunk servers haven't responded within HEALTH_CHECK_TIMEOUT
- Sets appropriate poll() timeout to wake up for next health check
The implementation ensures that:
- Chunk servers receive regular synchronization messages with add_list/rem_list
- The metadata server tracks chunk server health based on response times
- STATE_UPDATE messages are sent periodically (every 30 seconds by default)
- Failed/missing chunks are detected and logged for recovery
This completes the health check mechanism described in the architecture design,
enabling the metadata server to maintain accurate state with chunk servers and
detect unhealthy servers.
Unified the function signatures across all process types (metadata server,
chunk server, and simulation client) to accept an int *timeout parameter.
This provides consistency in the simulation framework and allows all
process types to control their wakeup times.
**Changes:**
**Headers (metadata_server.h, chunk_server.h):**
- Updated metadata_server_init() to accept int *timeout parameter
- Updated metadata_server_step() to accept int *timeout parameter
- Updated chunk_server_init() to accept int *timeout parameter
- Updated chunk_server_step() to accept int *timeout parameter
**Implementations (metadata_server.c, chunk_server.c):**
- Modified init functions to set *timeout = -1 (no timeout needed)
- Modified step functions to set *timeout = -1 (no timeout needed)
- Both server types currently don't require periodic wakeups, but the
parameter allows for future timeout-based behavior
**System Integration (system.c):**
- Updated spawn_simulated_process() to declare timeout variable once
and pass it to all process init functions uniformly
- Updated update_simulation() to declare timeout variable once and
pass it to all process step functions uniformly
- Simplified control flow by removing special case for client timeout
handling - now all process types use the same timeout logic
- Consolidated timeout-to-wakeup_time conversion after switch statements
**Benefits:**
- Consistent API across all process types
- Cleaner code with reduced duplication
- Future-proof for server timeout requirements
- All processes now managed uniformly by simulation framework
The simulation continues to run correctly with all process types
handling timeout parameter appropriately.
cozis
Claude