Files
hkuds--lightrag/lightrag/kg/json_kv_impl.py
T
2026-07-13 12:08:54 +08:00

493 lines
22 KiB
Python

import os
from dataclasses import dataclass
from typing import Any, final
from lightrag.base import (
BaseKVStorage,
)
from lightrag.file_atomic import reap_orphan_tmp_files
from lightrag.utils import (
_cooperative_yield,
load_json,
logger,
validate_workspace,
write_json,
)
from lightrag.exceptions import StorageNotInitializedError
from .shared_storage import (
get_namespace_data,
get_namespace_lock,
get_data_init_lock,
get_update_flag,
set_all_update_flags,
clear_all_update_flags,
try_initialize_namespace,
)
@final
@dataclass
class JsonKVStorage(BaseKVStorage):
"""JSON-file-backed KV storage with **shared in-memory state across processes**.
This class uses a *fundamentally different* cross-process model from
``NanoVectorDBStorage`` / ``FaissVectorDBStorage`` / ``NetworkXStorage``
(which keep one in-memory copy per process and reconcile via file
reloads). Compare carefully before changing either side.
Storage model:
``self._data`` is **not** a per-process dict — it is the value
returned by ``get_namespace_data(namespace, workspace=...)``, i.e.
a reference into ``shared_storage._shared_dicts``. In multi-
process mode this is a ``multiprocessing.Manager().dict()`` proxy
that every worker sees the **same instance** of; in single-
process mode it degrades to a plain ``dict``. Either way, a
mutation in any process is *immediately* visible to every other
process — there is no reload needed.
The on-disk file at
``working_dir/[workspace/]kv_store_<namespace>.json`` exists for
durability only. It is the source of truth at startup and the
target of ``index_done_callback`` flushes, but is **not** part of
the steady-state read/write path.
First-time load (``initialize``):
``try_initialize_namespace`` is a global init lock that returns
``True`` to exactly one process per ``(namespace, workspace)``.
That process reads the JSON file and populates ``self._data``
under ``_storage_lock``. Other processes skip the load — they
will see the data through the same shared ``self._data`` proxy.
Cross-process sync protocol (note: reversed semantics vs file-backed
classes):
Anyone writing (``upsert`` / ``delete`` / ``drop``):
1. Mutate ``self._data`` under ``_storage_lock`` (same lock,
same dict, all processes see the change immediately).
2. Call ``set_all_update_flags`` to mark **every** process's
``storage_updated`` flag ``True``. Here ``True`` means
*"there is dirty data that still needs to be flushed"*,
not *"there is fresher data on disk that I need to
reload"* as in the file-backed implementations.
Commit (``index_done_callback``):
1. Under ``_storage_lock``, if ``storage_updated.value`` is
``True``, snapshot ``self._data`` and write it to disk
via ``write_json`` (atomic).
2. ``clear_all_update_flags`` — wipe every process's flag
back to ``False``. Because the in-memory state is already
consistent across processes, there is nothing for the
*other* processes to do; the clear is just a
"the dirty data has been persisted" signal.
Lock scope:
``_storage_lock`` is a per-``(namespace, workspace)`` keyed lock
spanning intra-process coroutines **and** inter-process workers.
Unlike the file-backed classes (which only lock reload/commit
critical sections), this class **holds the lock over every
``self._data`` access** — read or write — because the underlying
``Manager().dict()`` is not free-threaded across processes.
Two places intentionally do work outside the lock for latency
reasons:
* ``upsert`` performs its per-key timestamp prep loop inside
the lock but yields to the event loop via
``_cooperative_yield`` between keys (safe: ``NamespaceLock``
is non-reentrant, so siblings blocked on it stay blocked).
* ``JsonDocStatusStorage.upsert`` prepares its caller-supplied
dict outside the lock (it only mutates the input, not the
shared store).
Who can write:
Pipeline ``busy`` still serializes the document ingest / purge
flows, but the *file-flush trigger* is symmetric: any process
whose ``storage_updated.value`` is ``True`` when
``index_done_callback`` fires will perform the write. In a
single-writer pipeline this is always the same process; if you
ever permit multiple writers, two processes may race to flush
the same in-memory state — that race is safe (both flush the
same shared dict, ``write_json`` is atomic per file) but
wasteful, and the ``clear_all_update_flags`` after each flush
means subsequent re-flushes are no-ops.
Caveats vs file-backed implementations:
* **No reload path.** If something writes to the on-disk file
out of band, this class will not pick it up until restart.
The file is only ever written by ``index_done_callback`` and
read once in ``initialize``.
* **No ``_get_*`` entry method.** Adding one would be wrong —
there's nothing to "get fresher than" since the in-memory
state is already the shared, authoritative view.
* **``write_json`` may sanitize.** If sanitization happens, the
on-disk JSON differs from what was in memory; the callback
re-reads the cleaned file back into ``self._data`` under the
same lock so the shared view stays consistent with disk.
Non-pipeline write paths:
* ``drop`` — destructive, **not** serialized by this storage
class. Currently gated by the API layer
(``/documents/clear``); any new caller must hold the pipeline
``busy`` reservation.
* ``upsert`` / ``delete`` invoked from non-pipeline admin flows
(cache management, etc.) — safe under the shared-lock model,
but consumers should still respect the pipeline gate to avoid
interleaving with batched ingest work.
"""
def __post_init__(self):
# Reject path traversal before using workspace in a file path
validate_workspace(self.workspace)
working_dir = self.global_config["working_dir"]
if self.workspace:
# Include workspace in the file path for data isolation
workspace_dir = os.path.join(working_dir, self.workspace)
else:
# Default behavior when workspace is empty
workspace_dir = working_dir
self.workspace = ""
os.makedirs(workspace_dir, exist_ok=True)
self._file_name = os.path.join(workspace_dir, f"kv_store_{self.namespace}.json")
self._data = None
self._storage_lock = None
self.storage_updated = None
reap_orphan_tmp_files(self._file_name, self.workspace or "_")
async def initialize(self):
"""Bind to the shared namespace dict and load from disk on first init.
``try_initialize_namespace`` is a global init lock that returns
``True`` for exactly one process per ``(namespace, workspace)``;
that process reads the JSON file and populates the shared
``self._data`` under ``_storage_lock``. Subsequent processes
skip the file read — they will see the same shared dict via
``get_namespace_data``.
For ``*_cache`` namespaces an extra
``_migrate_legacy_cache_structure`` pass runs against the loaded
data and may rewrite the on-disk file if a migration was applied.
"""
self._storage_lock = get_namespace_lock(
self.namespace, workspace=self.workspace
)
self.storage_updated = await get_update_flag(
self.namespace, workspace=self.workspace
)
async with get_data_init_lock():
# check need_init must before get_namespace_data
need_init = await try_initialize_namespace(
self.namespace, workspace=self.workspace
)
self._data = await get_namespace_data(
self.namespace, workspace=self.workspace
)
if need_init:
loaded_data = load_json(self._file_name) or {}
async with self._storage_lock:
# Migrate legacy cache structure if needed
if self.namespace.endswith("_cache"):
loaded_data = await self._migrate_legacy_cache_structure(
loaded_data
)
self._data.update(loaded_data)
data_count = len(loaded_data)
logger.info(
f"[{self.workspace}] Process {os.getpid()} KV load {self.namespace} with {data_count} records"
)
async def index_done_callback(self) -> None:
"""Flush dirty in-memory state to disk and clear all dirty flags.
Commit point in the shared-memory protocol (see class docstring,
*Cross-process sync protocol*). Steps:
1. Under ``_storage_lock``, check this process's
``storage_updated.value``. If ``False``, nothing to do —
return.
2. Snapshot ``self._data`` (converting from ``Manager.dict``
proxy to a plain ``dict`` so the JSON encoder doesn't trip
over the proxy) and write it via ``write_json``.
3. If ``write_json`` reports sanitization was applied, the
on-disk file no longer matches what was in memory — reload
the cleaned data back into ``self._data`` under the same
lock so the shared view stays consistent.
4. ``clear_all_update_flags`` — wipe every process's
``storage_updated`` flag back to ``False``, signaling
that the dirty data has been persisted.
Note the **semantic difference** from the file-backed classes'
commit: there is no ``set_all_update_flags`` here. The shared
dict is already consistent across processes; the only thing
``index_done_callback`` does globally is *clear* the dirty
flags.
"""
async with self._storage_lock:
if self.storage_updated.value:
data_dict = (
dict(self._data) if hasattr(self._data, "_getvalue") else self._data
)
# Calculate data count - all data is now flattened
data_count = len(data_dict)
logger.debug(
f"[{self.workspace}] Process {os.getpid()} KV writting {data_count} records to {self.namespace}"
)
# Write JSON and check if sanitization was applied
needs_reload = write_json(data_dict, self._file_name)
# If data was sanitized, reload cleaned data to update shared memory
if needs_reload:
logger.info(
f"[{self.workspace}] Reloading sanitized data into shared memory for {self.namespace}"
)
cleaned_data = load_json(self._file_name)
if cleaned_data is not None:
self._data.clear()
self._data.update(cleaned_data)
await clear_all_update_flags(self.namespace, workspace=self.workspace)
async def get_by_id(self, id: str) -> dict[str, Any] | None:
async with self._storage_lock:
result = self._data.get(id)
if result:
# Create a copy to avoid modifying the original data
result = dict(result)
# Ensure time fields are present, provide default values for old data
result.setdefault("create_time", 0)
result.setdefault("update_time", 0)
# Ensure _id field contains the clean ID
result["_id"] = id
return result
async def get_by_ids(self, ids: list[str]) -> list[dict[str, Any]]:
async with self._storage_lock:
results = []
for id in ids:
data = self._data.get(id, None)
if data:
# Create a copy to avoid modifying the original data
result = {k: v for k, v in data.items()}
# Ensure time fields are present, provide default values for old data
result.setdefault("create_time", 0)
result.setdefault("update_time", 0)
# Ensure _id field contains the clean ID
result["_id"] = id
results.append(result)
else:
results.append(None)
return results
async def filter_keys(self, keys: set[str]) -> set[str]:
async with self._storage_lock:
return set(keys) - set(self._data.keys())
async def upsert(self, data: dict[str, dict[str, Any]]) -> None:
"""Insert or update KV records in shared memory; mark all processes dirty.
Two side effects under ``_storage_lock``:
1. Stamp ``create_time`` / ``update_time`` / ``_id`` on each
value, then ``self._data.update(data)``. Because
``self._data`` is the shared ``Manager.dict()`` proxy, the
update is visible to all processes immediately — no
reload needed.
2. ``set_all_update_flags`` — flip every process's
``storage_updated.value`` to ``True``. Here ``True``
means *"there is dirty data that still needs to be
flushed to disk"*, **not** *"there is fresher data on
disk"* as in the file-backed classes (see class docstring
for the contrast).
Persistence is deferred to the next ``index_done_callback`` (the
pipeline calls this via ``_insert_done()`` after each batch).
Note: the per-key prep loop calls ``_cooperative_yield`` inside
the lock. That is safe because ``NamespaceLock`` is non-
reentrant — siblings waiting on this lock stay blocked across
the yield; only unrelated coroutines benefit from the yield.
"""
if not data:
return
import time
current_time = int(time.time()) # Get current Unix timestamp
logger.debug(
f"[{self.workspace}] Inserting {len(data)} records to {self.namespace}"
)
if self._storage_lock is None:
raise StorageNotInitializedError("JsonKVStorage")
async with self._storage_lock:
# Add timestamps to data based on whether key exists.
# The loop reads self._data (k in self._data) so it must stay inside
# the lock. _cooperative_yield is safe here: NamespaceLock is
# non-reentrant, so other coroutines waiting on this lock will block
# until we release it; the yield only benefits unrelated coroutines.
for i, (k, v) in enumerate(data.items(), start=1):
# For text_chunks namespace, ensure llm_cache_list field exists
if self.namespace.endswith("text_chunks"):
if "llm_cache_list" not in v:
v["llm_cache_list"] = []
# Add timestamps based on whether key exists
if k in self._data: # Key exists, only update update_time
v["update_time"] = current_time
else: # New key, set both create_time and update_time
v["create_time"] = current_time
v["update_time"] = current_time
v["_id"] = k
await _cooperative_yield(i)
self._data.update(data)
await set_all_update_flags(self.namespace, workspace=self.workspace)
async def delete(self, ids: list[str]) -> None:
"""Remove records from shared memory; mark all processes dirty if any deleted.
Under ``_storage_lock``: ``self._data.pop(doc_id, None)`` for
each id. Only calls ``set_all_update_flags`` if at least one key
was actually present (avoids creating spurious dirty state for
no-op deletes).
See class docstring for the shared-memory + dirty-flag protocol
and the semantic contrast vs file-backed classes.
Args:
ids: List of document IDs to be deleted from storage
"""
async with self._storage_lock:
any_deleted = False
for doc_id in ids:
result = self._data.pop(doc_id, None)
if result is not None:
any_deleted = True
if any_deleted:
await set_all_update_flags(self.namespace, workspace=self.workspace)
async def is_empty(self) -> bool:
"""Check if the storage is empty
Returns:
bool: True if storage contains no data, False otherwise
"""
async with self._storage_lock:
return len(self._data) == 0
async def drop(self) -> dict[str, str]:
"""Clear shared memory and immediately persist the empty state.
This method will:
1. Clear the shared ``self._data`` dict under
``_storage_lock`` (visible to all processes immediately).
2. ``set_all_update_flags`` so every process knows there is
dirty state pending persistence.
3. Call ``index_done_callback`` synchronously to flush the
empty state to disk and clear the dirty flags.
Caller contract:
``drop`` is destructive and **not** serialized by this
storage class. The caller must hold the pipeline ``busy``
reservation (the ``/documents/clear`` endpoint does this)
before invoking it — running ``drop`` concurrently with an
active document pipeline will wipe out in-flight work and
silently lose data. See class docstring,
*Non-pipeline write paths*.
Returns:
dict[str, str]: Operation status and message
- On success: {"status": "success", "message": "data dropped"}
- On failure: {"status": "error", "message": "<error details>"}
"""
try:
async with self._storage_lock:
self._data.clear()
await set_all_update_flags(self.namespace, workspace=self.workspace)
await self.index_done_callback()
logger.info(
f"[{self.workspace}] Process {os.getpid()} drop {self.namespace}"
)
return {"status": "success", "message": "data dropped"}
except Exception as e:
logger.error(f"[{self.workspace}] Error dropping {self.namespace}: {e}")
return {"status": "error", "message": str(e)}
async def _migrate_legacy_cache_structure(self, data: dict) -> dict:
"""Migrate legacy nested cache structure to flattened structure
Args:
data: Original data dictionary that may contain legacy structure
Returns:
Migrated data dictionary with flattened cache keys (sanitized if needed)
"""
from lightrag.utils import generate_cache_key
# Early return if data is empty
if not data:
return data
# Check first entry to see if it's already in new format
first_key = next(iter(data.keys()))
if ":" in first_key and len(first_key.split(":")) == 3:
# Already in flattened format, return as-is
return data
migrated_data = {}
migration_count = 0
for key, value in data.items():
# Check if this is a legacy nested cache structure
if isinstance(value, dict) and all(
isinstance(v, dict) and "return" in v for v in value.values()
):
# This looks like a legacy cache mode with nested structure
mode = key
for cache_hash, cache_entry in value.items():
cache_type = cache_entry.get("cache_type", "extract")
flattened_key = generate_cache_key(mode, cache_type, cache_hash)
migrated_data[flattened_key] = cache_entry
migration_count += 1
else:
# Keep non-cache data or already flattened cache data as-is
migrated_data[key] = value
if migration_count > 0:
logger.info(
f"[{self.workspace}] Migrated {migration_count} legacy cache entries to flattened structure"
)
# Persist migrated data immediately and check if sanitization was applied
needs_reload = write_json(migrated_data, self._file_name)
# If data was sanitized during write, reload cleaned data
if needs_reload:
logger.info(
f"[{self.workspace}] Reloading sanitized migration data for {self.namespace}"
)
cleaned_data = load_json(self._file_name)
if cleaned_data is not None:
return cleaned_data # Return cleaned data to update shared memory
return migrated_data
async def finalize(self):
"""On shutdown, flush ``*_cache`` namespaces to disk.
Cache namespaces are routinely written to during query/extract
without triggering an immediate ``index_done_callback`` (caches
churn fast and the pipeline doesn't always end at a natural
commit point). This hook ensures whatever dirty cache state is
in shared memory at process exit gets persisted, so the next
run can pick it up.
Non-cache namespaces don't need this — their writes already
flow through pipeline-driven ``_insert_done()`` commits.
"""
if self.namespace.endswith("_cache"):
await self.index_done_callback()