Server Configuration File

ChronoLog server executables share a single JSON configuration file. The repository ships a template at default_conf.json.in; a fully expanded example is installed as conf/default-chrono-conf.json and is used by tools/deploy/deploy_local.sh.

As of ChronoLog v2.8.0 the file is organized into two shared blocks (clock, authentication) and four per-component sections (chrono_visor, chrono_keeper, chrono_grapher, chrono_player). See the Overview page for the loader architecture behind these sections.

{
  "clock":          { ... },
  "authentication": { ... },
  "chrono_visor":   { ... },
  "chrono_keeper":  { ... },
  "chrono_grapher": { ... },
  "chrono_player":  { ... }
}

---

Shared Blocks

These blocks are parsed once by ConfigurationManager and are visible to every process.

clock

Controls the clock source used for event timestamping. See Performance Tuning → Clock Source for the effect of each option.

Field	Type	Default	Description
clocksource_type	string	"CPP_STYLE"	One of "C_STYLE", "CPP_STYLE", "TSC".
drift_cal_sleep_sec	integer	10	Seconds between clock drift calibrations.
drift_cal_sleep_nsec	integer	0	Additional nanoseconds added to the calibration interval.

Backed by ClockConf in src/chrono-common/include/ConfigurationBlocks.h.

authentication

Field	Type	Default	Description
auth_type	string	"RBAC"	Authentication mechanism. Currently only "RBAC" is used.
module_location	string	""	Path to the authentication module shared object.

Backed by AuthConf in src/chrono-common/include/ConfigurationBlocks.h.

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Common Per-Component Sub-Blocks

Several JSON sub-blocks appear in more than one component. They always have the same shape, parsed by the same C++ building block.

rpc — Thallium endpoint

Every service endpoint is described by an rpc block, parsed by RPCProviderConf.

Field	Type	Example	Description
protocol_conf	string	"ofi+sockets"	Thallium/Mercury transport string. See Network & RPC.
service_ip	string	"127.0.0.1"	IP the service binds to (servers) or connects to (clients).
service_base_port	integer	5555	TCP port.
service_provider_id	integer	55	Thallium provider ID; multiplexes services on the same address.

Monitoring — logging

Per-component log sink. Wrapped under a monitor key and parsed by LogConf.

"Monitoring": {
  "monitor": {
    "type": "file",
    "file": "chrono-visor-1.log",
    "level": "debug",
    "name": "ChronoVisor",
    "filesize": 104857600,
    "filenum": 3,
    "flushlevel": "warning"
  }
}

Field	Type	Description
type	string	Log sink type. Currently only "file" is supported.
file	string	Log file name.
level	string	Minimum log level: trace, debug, info, warning, error, critical, off.
name	string	Logger name that appears in log lines.
filesize	integer	Maximum file size in bytes before rotation.
filenum	integer	Number of rotated files to keep.
flushlevel	string	Minimum level that triggers an immediate flush to disk.

DataStoreInternals — story-chunk tuning

Appears in chrono_keeper, chrono_grapher, and chrono_player. Parsed by DataStoreConf. See Performance Tuning → Story Chunk Settings for the semantics of each field.

Field	Type	Description
max_story_chunk_size	integer	Maximum number of events in a single chunk.
story_chunk_duration_secs	integer	How long a chunk remains open.
acceptance_window_secs	integer	Maximum allowed age of an incoming event relative to wall-clock time.
inactive_story_delay_secs	integer	Idle time before an in-memory story is evicted.

ExtractionModule

Present under chrono_keeper and chrono_grapher. Parsed by ExtractionModuleConfiguration (src/chrono-common/include/ExtractionModuleConfiguration.h). Defines the configurable pipeline of extractors that drains retired StoryChunks. See Architecture → ChronoKeeper for the concept and Performance Tuning → Extraction Pipeline for tuning guidance.

Field	Type	Description
extraction_stream_count	integer	Number of parallel extraction-stream threads draining the extraction queue. Default: 2.
extraction_protocol	string	Thallium protocol used by RDMA-based extractors. Default: "ofi+sockets".
extractors	object	Map of extractor instances keyed by an arbitrary label. Each entry must set "type" to one of the supported extractor types listed below; additional fields depend on the type.

Supported extractor types

type	Available in	Required fields	Behavior
csv_extractor	keeper, grapher	csv_archive_dir (string)	Writes each StoryChunk as a CSV file under csv_archive_dir.
single_endpoint_rdma_extractor	keeper, grapher	receiving_endpoint (object: protocol_conf, service_ip, service_base_port, service_provider_id)	Drains each StoryChunk to one RDMA endpoint (typically a ChronoGrapher's KeeperGrapherDrainService).
dual_endpoint_rdma_extractor	keeper	Two receiving_endpoint entries	Fans each StoryChunk out to two RDMA endpoints simultaneously (e.g. ChronoGrapher + ChronoPlayer).
hdf5_extractor	grapher	hdf5_archive_dir (string)	Serializes each StoryChunk into the HDF5 archive under hdf5_archive_dir.

See the keeper and grapher blocks in conf/default_conf.json.in for fully expanded examples.

ArchiveReaders — story files directory

Present under chrono_player. Parsed by ExtractorReaderConf.

Field	Type	Description
story_files_dir	string	Filesystem directory where archived story files are read from by the player.

IngestionThreadCount — ingestion-thread parallelism

A scalar field that sits inside the ingestion service object of each component:

Component	Path	Default	Description
ChronoKeeper	chrono_keeper.KeeperRecordingService.IngestionThreadCount	4	Number of worker threads serving the Keeper recording RPC.
ChronoGrapher	chrono_grapher.KeeperGrapherDrainService.IngestionThreadCount	1	Number of worker threads serving the Grapher drain RPC.
ChronoPlayer	chrono_player.PlaybackQueryService.IngestionThreadCount	1	Number of worker threads serving the Player playback-query RPC.

---

chrono_visor

Parsed by VisorConfiguration (src/chrono-visor/include/ChronoVisorConfiguration.h).

Field	Type	Description
VisorClientPortalService	object	{ "rpc": { ... } } — endpoint used by clients to connect to ChronoVisor.
VisorKeeperRegistryService	object	{ "rpc": { ... } } — endpoint where ChronoKeeper/Grapher/Player register and heartbeat.
Monitoring	object	See Monitoring.
delayed_data_admin_exit_in_secs	integer	Shutdown grace period for the data administration service. Clamped to (0, 60); default 5.

chrono_keeper

Parsed by KeeperConfiguration (src/chrono-keeper/include/ChronoKeeperConfiguration.h).

Field	Type	Description
RecordingGroup	integer	Logical group this keeper belongs to. Must match its paired ChronoGrapher.
KeeperRecordingService	object	{ "rpc": { ... } } — endpoint that receives events from ChronoVisor for recording.
KeeperDataStoreAdminService	object	{ "rpc": { ... } } — endpoint for admin actions on the keeper's data store.
VisorKeeperRegistryService	object	{ "rpc": { ... } } — endpoint on ChronoVisor where this keeper registers.
KeeperGrapherDrainService	object	{ "rpc": { ... } } — endpoint on ChronoGrapher where drained chunks are delivered.
Monitoring	object	See Monitoring.
DataStoreInternals	object	See DataStoreInternals.
ExtractionModule	object	See ExtractionModule.

KeeperRecordingService carries an IngestionThreadCount field — see IngestionThreadCount.

chrono_grapher

Parsed by GrapherConfiguration (src/chrono-grapher/include/ChronoGrapherConfiguration.h).

Field	Type	Description
RecordingGroup	integer	Logical group this grapher serves.
KeeperGrapherDrainService	object	{ "rpc": { ... } } — endpoint where this grapher receives drained chunks from a keeper.
DataStoreAdminService	object	{ "rpc": { ... } } — endpoint for admin actions on the grapher's data store.
VisorRegistryService	object	{ "rpc": { ... } } — endpoint on ChronoVisor where this grapher registers.
Monitoring	object	See Monitoring.
DataStoreInternals	object	See DataStoreInternals.
ExtractionModule	object	See ExtractionModule.

KeeperGrapherDrainService carries an IngestionThreadCount field — see IngestionThreadCount.

chrono_player

Parsed by PlayerConfiguration (src/chrono-player/include/ChronoPlayerConfiguration.h).

Field	Type	Description
RecordingGroup	integer	Logical group this player serves.
PlayerStoreAdminService	object	{ "rpc": { ... } } — endpoint for admin actions on the player's data store.
PlaybackQueryService	object	{ "rpc": { ... } } — endpoint that receives playback queries from clients.
VisorRegistryService	object	{ "rpc": { ... } } — endpoint on ChronoVisor where this player registers.
Monitoring	object	See Monitoring.
DataStoreInternals	object	See DataStoreInternals.
ArchiveReaders	object	See ArchiveReaders.

PlaybackQueryService carries an IngestionThreadCount field — see IngestionThreadCount.

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Full Example

The repository ships a fully expanded example at conf/default_conf.json.in. Default values for every field are defined in the constructors of the configuration classes listed above.