perf(memory): hoist loop-invariant HRR encodes out of retrieval loops

FactRetriever.search() re-encoded the query vector once per candidate,
related() re-encoded both role atoms once per fact row, and probe()
re-encoded the role-content atom once per row. All three encoders are
deterministic (SHA-256 counter blocks), so the hoisted vectors are
bit-identical to the per-iteration values they replace.

Measured (300-fact store, dim=1024, median of 30 calls): search()
11.62 -> 1.46 ms/call (8.0x; encode_text 30 -> 1 per call), related()
63.08 -> 16.17 ms/call (3.9x; encode_atom 601 -> 3 per call), probe()
431.93 -> 389.36 ms/call (1.1x; dominated by per-fact content encoding,
which is inherent to the algorithm and unchanged).

Tests: call-count regression tests for each hoist plus a bit-exact
parity test of search() against the pre-fix per-candidate loop.
This commit is contained in:
spfcraze
2026-08-01 07:04:16 -04:00
committed by kshitij
parent 8f91e249e4
commit 89f74d58f6
2 changed files with 156 additions and 4 deletions
+18 -4
View File
@@ -70,6 +70,15 @@ class FactRetriever:
# Stage 2: Rerank with Jaccard + trust + optional decay
query_tokens = self._tokenize(query)
# The query vector is loop-invariant — encode it at most once, on
# the first candidate that actually carries an HRR vector. Lazy on
# purpose: migrated stores can have FTS candidates whose hrr_vector
# was never backfilled (MemoryStore._init_db adds the column
# without backfilling), and those must not pay for an encode
# nothing will use. encode_text is deterministic (SHA-256 counter
# blocks), so the hoisted vector is bit-identical to what the
# per-candidate calls produced.
query_vec = None
scored = []
for fact in candidates:
@@ -83,7 +92,8 @@ class FactRetriever:
# HRR similarity
if self.hrr_weight > 0 and fact.get("hrr_vector"):
fact_vec = hrr.bytes_to_phases(fact["hrr_vector"])
query_vec = hrr.encode_text(query, self.hrr_dim)
if query_vec is None:
query_vec = hrr.encode_text(query, self.hrr_dim)
hrr_sim = (hrr.similarity(query_vec, fact_vec) + 1.0) / 2.0 # shift to [0,1]
else:
hrr_sim = 0.5 # neutral
@@ -173,6 +183,9 @@ class FactRetriever:
# Final fallback: keyword search
return self.search(entity, category=category, limit=limit)
# role_content is loop-invariant — encode it once (deterministic
# SHA-256-based atom) instead of once per fact row.
role_content = hrr.encode_atom("__hrr_role_content__", self.hrr_dim)
scored = []
for row in rows:
fact = dict(row)
@@ -180,7 +193,6 @@ class FactRetriever:
# Unbind probe key from fact to see if entity is structurally present
residual = hrr.unbind(fact_vec, probe_key)
# Compare residual against content signal
role_content = hrr.encode_atom("__hrr_role_content__", self.hrr_dim)
content_vec = hrr.bind(hrr.encode_text(fact["content"], self.hrr_dim), role_content)
sim = hrr.similarity(residual, content_vec)
fact["score"] = (sim + 1.0) / 2.0 * fact["trust_score"]
@@ -234,6 +246,10 @@ class FactRetriever:
# Score each fact by how much the entity's atom appears in its vector
# This catches both role-bound entity matches AND content word matches
# Both role atoms are loop-invariant — encode them once here
# (deterministic SHA-256-based atoms) instead of twice per fact row.
role_entity = hrr.encode_atom("__hrr_role_entity__", self.hrr_dim)
role_content = hrr.encode_atom("__hrr_role_content__", self.hrr_dim)
scored = []
for row in rows:
fact = dict(row)
@@ -243,8 +259,6 @@ class FactRetriever:
residual = hrr.unbind(fact_vec, entity_vec)
# A high-similarity residual to ANY known role vector means this entity
# plays a structural role in the fact
role_entity = hrr.encode_atom("__hrr_role_entity__", self.hrr_dim)
role_content = hrr.encode_atom("__hrr_role_content__", self.hrr_dim)
entity_role_sim = hrr.similarity(residual, role_entity)
content_role_sim = hrr.similarity(residual, role_content)
@@ -95,3 +95,141 @@ def test_prefetch_recovers_prose_query(retriever_with_facts):
assert "deployment rollback" in results[0]["content"].lower()
# ---------------------------------------------------------------------------
# Loop-invariant encode hoists (perf) — search/probe/related must encode
# constant vectors ONCE per call, not once per candidate/row.
# encode_text/encode_atom are deterministic (SHA-256 counter blocks), so the
# hoisted vectors are bit-identical to the per-iteration values they replace.
# ---------------------------------------------------------------------------
from plugins.memory.holographic import holographic as hrr
@pytest.fixture
def hoisted_retriever():
"""30 facts with HRR vectors, default dim (smaller dims trip an
inhomogeneous-shape edge in the fact encoder)."""
store = MemoryStore(":memory:")
for i in range(30):
store.add_fact(
content=f"deploy target {i} setting alpha beta gamma option {i % 7}",
category="fact" if i % 2 else "preference",
tags=f"entity_{i % 5} deploy",
)
retriever = FactRetriever(store=store)
yield retriever
store.close()
def _counting_spy(monkeypatch, attr):
calls = []
real = getattr(hrr, attr)
def wrapper(*args, **kwargs):
calls.append(args)
return real(*args, **kwargs)
monkeypatch.setattr(hrr, attr, wrapper)
return calls
def test_encode_functions_are_deterministic():
"""Soundness premise of the hoists: same input -> identical vector."""
import numpy as np
assert np.array_equal(hrr.encode_text("deploy target", 1024),
hrr.encode_text("deploy target", 1024))
assert np.array_equal(hrr.encode_atom("__hrr_role_content__", 1024),
hrr.encode_atom("__hrr_role_content__", 1024))
def test_search_encodes_query_vector_once(hoisted_retriever, monkeypatch):
calls = _counting_spy(monkeypatch, "encode_text")
results = hoisted_retriever.search("deploy target setting")
assert results # the HRR path actually engaged
assert len(calls) == 1, (
f"query vector encoded {len(calls)}x in one search() — "
"loop-invariant hoist regressed"
)
def test_search_results_bit_identical_to_unhoisted(hoisted_retriever):
"""Parity: hoisted search() must produce the exact pre-fix results.
Replicates the pre-fix loop (query vector encoded per candidate) as the
reference and compares full scored output for exact equality.
"""
r = hoisted_retriever
query = "deploy target setting"
new_results = r.search(query)
# --- pre-fix reference ---
candidates = r._fts_candidates(query, None, 0.3, 10 * 3)
query_tokens = r._tokenize(query)
scored = []
for fact in candidates:
content_tokens = r._tokenize(fact["content"])
tag_tokens = r._tokenize(fact.get("tags", ""))
all_tokens = content_tokens | tag_tokens
jaccard = r._jaccard_similarity(query_tokens, all_tokens)
fts_score = fact.get("fts_rank", 0.0)
if r.hrr_weight > 0 and fact.get("hrr_vector"):
fact_vec = hrr.bytes_to_phases(fact["hrr_vector"])
query_vec = hrr.encode_text(query, r.hrr_dim) # per-candidate
hrr_sim = (hrr.similarity(query_vec, fact_vec) + 1.0) / 2.0
else:
hrr_sim = 0.5
relevance = (r.fts_weight * fts_score
+ r.jaccard_weight * jaccard
+ r.hrr_weight * hrr_sim)
fact["score"] = relevance * fact["trust_score"]
scored.append(fact)
scored.sort(key=lambda x: x["score"], reverse=True)
old_results = scored[:10]
for fact in old_results:
fact.pop("hrr_vector", None)
assert new_results == old_results
def test_related_encodes_role_atoms_once(hoisted_retriever, monkeypatch):
calls = _counting_spy(monkeypatch, "encode_atom")
results = hoisted_retriever.related("entity_1")
assert results
role_calls = [a for a in calls
if a and str(a[0]).startswith("__hrr_role_")]
assert len(role_calls) == 2, (
f"role atoms encoded {len(role_calls)}x in one related() — "
"expected exactly 2 (role_entity + role_content, hoisted)"
)
def test_probe_encodes_role_atom_once(hoisted_retriever, monkeypatch):
calls = _counting_spy(monkeypatch, "encode_atom")
results = hoisted_retriever.probe("entity_1")
assert results
role_content_calls = [a for a in calls
if a and a[0] == "__hrr_role_content__"]
assert len(role_content_calls) == 1, (
f"role_content atom encoded {len(role_content_calls)}x in one "
"probe() — loop-invariant hoist regressed"
)
def test_search_without_vectors_never_encodes(hoisted_retriever, monkeypatch):
"""Migrated DBs can have FTS candidates with NULL hrr_vector
(MemoryStore._init_db adds the column without backfilling existing
facts). The lazy hoist must not encode a query vector nothing will
use — pre-fix main encoded only beneath fact.get('hrr_vector')."""
store = hoisted_retriever.store
store._conn.execute("UPDATE facts SET hrr_vector = NULL")
store._conn.commit()
calls = _counting_spy(monkeypatch, "encode_text")
results = hoisted_retriever.search("deploy target setting")
assert results # candidates exist; neutral hrr_sim=0.5 path
assert calls == [], (
f"encode_text called {len(calls)}x with zero vector candidates — "
"lazy hoist regressed to eager"
)