558 lines
22 KiB
Rust
558 lines
22 KiB
Rust
//! Compact / prune 専用のトークン会計補助。
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//!
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//! 汎用部分（`prefix_bytes`, `tokens_at`, `total_tokens`, `total_tokens_at`）は
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//! [`llm_worker::token_counter`] にあり、`UsageRecord` の列と現在の history から
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//! pure に推定する。本モジュールは compact / prune 固有のロジック
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//! （`split_for_retained`, `savings_for_prune`）と、Pod 上の公開 API に
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//! 限定する。
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//!
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//! # 方針
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//!
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//! - ローカルトークナイザは持たない。実測値があればそれを採用し、
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//! measurement 間はバイト数で按分、最新 measurement より先は最終 rate で外挿する
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//! - Compact の retained split では、request-time pruning / projection 後の
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//! `UsageRecord` を persisted history prefix の単調系列として扱わない。
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//! 現在の prompt occupancy 推定を raw serialized bytes に配分し、末尾の
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//! persisted tail サイズで cut を決める。
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//! - 推定の出どころは [`EstimateSource`] で呼び出し側に明示する。
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//! 課金判断には使えないが、compact / prune の閾値判定には十分な精度
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use llm_worker::llm_client::client::LlmClient;
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use llm_worker::token_counter::{item_bytes, prefix_bytes, tokens_at};
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use llm_worker::{Item, UsageRecord};
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use session_store::Store;
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pub use llm_worker::token_counter::{EstimateSource, TokenEstimate};
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use crate::Pod;
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/// history を分割する位置。
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///
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/// `items[..index]` が捨てる／要約される側、`items[index..]` が残る側。
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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pub struct SplitPoint {
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pub index: usize,
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pub source: EstimateSource,
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}
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fn split_for_retained_impl(history: &[Item], records: &[UsageRecord], retained: u64) -> SplitPoint {
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let prefix = prefix_bytes(history);
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let current = tokens_at(history, records, history.len(), &prefix);
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if current.tokens <= retained {
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return SplitPoint {
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index: 0,
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source: current.source,
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};
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}
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let cut_index = split_index_by_retained_bytes(&prefix, current.tokens, retained);
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SplitPoint {
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index: balance_to_pair_boundary(history, cut_index),
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source: current.source,
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}
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}
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fn split_index_by_retained_bytes(prefix: &[u64], total_tokens: u64, retained_tokens: u64) -> usize {
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debug_assert!(!prefix.is_empty());
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let len = prefix.len() - 1;
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if len == 0 {
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return 0;
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}
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if retained_tokens == 0 {
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return len;
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}
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let total_bytes = *prefix.last().unwrap_or(&0);
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if total_bytes == 0 || total_tokens == 0 {
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return 0;
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}
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let raw_fallback_tokens = ceil_div_u128(total_bytes as u128, 4) as u64;
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let rate_tokens = total_tokens.max(raw_fallback_tokens);
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let target_retained_bytes = ceil_div_u128(
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retained_tokens as u128 * total_bytes as u128,
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rate_tokens as u128,
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)
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.min(total_bytes as u128) as u64;
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// Drop as many complete Items as possible while keeping the raw persisted
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// suffix at or above the retained budget. This is monotonic in serialized
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// history size and intentionally does not inspect per-history_len
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// UsageRecords: request-time usage can move up and down after pruning /
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// projection, so it is not a valid prefix series for retained split. The
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// byte/4 fallback is kept as a lower bound for raw persisted size so a
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// heavily-pruned request measurement cannot justify retaining megabytes of
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// history.
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let mut cut = 0;
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for (idx, bytes_before) in prefix.iter().enumerate().take(len + 1) {
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let suffix_bytes = total_bytes.saturating_sub(*bytes_before);
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if suffix_bytes >= target_retained_bytes {
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cut = idx;
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} else {
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break;
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}
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}
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cut
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}
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fn ceil_div_u128(n: u128, d: u128) -> u128 {
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debug_assert!(d > 0);
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if n == 0 { 0 } else { ((n - 1) / d) + 1 }
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}
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/// `history[cut..]` が `ToolCall` / `ToolResult` のペア境界を尊重するよう
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/// `cut` を後退させる。
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///
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/// LLM API は「`ToolResult` を送るならその `ToolCall` も同じ request に
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/// 含まれていなければならない」というバリデーションを持つ。トークン数
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/// だけで切った `cut` は並列 tool 呼び出しの途中に落ちうるので、retained
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/// 側の先頭に対応 `ToolCall` を持たない `ToolResult`（orphan）が残ると
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/// 次セッション初回 request が API バリデーションで弾かれる。
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///
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/// 対策は「retained に入る `ToolResult` について、対応 `ToolCall` も
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/// retained に含まれる位置まで `cut` を引き下げる」こと。retained_tokens
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/// 予算は超えうるが、ここでは直接 LLM に投げる訳ではなく次の
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/// `pre_llm_request` で再評価されるだけなので safe。
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///
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/// アルゴリズム: history を末尾から走査し、retained 範囲内の `ToolResult`
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/// に出会うたびに対応 `ToolCall` の位置で `cut` を min 更新する。`cut` が
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/// 下がると以前は要約側だった位置が retained に入るので、後続走査で連鎖的
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/// に正しい位置まで引き下がる。`ToolCall` の `call_id` はユニークなので
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/// 事前にマップ化して O(n) で済ます。
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fn balance_to_pair_boundary(history: &[Item], cut: usize) -> usize {
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let mut idx = cut.min(history.len());
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if idx == 0 {
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return 0;
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}
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let call_positions: std::collections::HashMap<&str, usize> = history
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.iter()
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.enumerate()
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.filter_map(|(i, item)| match item {
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Item::ToolCall { call_id, .. } => Some((call_id.as_str(), i)),
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_ => None,
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})
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.collect();
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let mut k = history.len();
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while k > 0 {
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k -= 1;
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if k >= idx {
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if let Item::ToolResult { call_id, .. } = &history[k] {
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if let Some(&call_pos) = call_positions.get(call_id.as_str()) {
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if call_pos < idx {
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idx = call_pos;
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}
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}
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}
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}
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}
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idx
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}
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/// 1 つの ToolResult 項目について、`content` を `None` に射影したとき
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/// 減少するシリアライズ後バイト数。ToolResult 以外や既に content=None
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/// の item は 0 を返す。
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fn tool_result_content_bytes(item: &Item) -> u64 {
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if !matches!(
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item,
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Item::ToolResult {
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content: Some(_),
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..
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}
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) {
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return 0;
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}
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let mut cleared = item.clone();
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if let Item::ToolResult { content, .. } = &mut cleared {
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*content = None;
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}
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item_bytes(item).saturating_sub(item_bytes(&cleared))
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}
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/// Prefix-boundary token estimates used by Prune to find its protected suffix.
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///
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/// Returns `history.len() + 1` entries where entry `i` estimates
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/// `history[..i]`. This shares the same [`tokens_at`] accounting as compact's
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/// retained-tail split and prune's savings estimate.
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pub(crate) fn token_estimates_for_prune_impl(
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history: &[Item],
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records: &[UsageRecord],
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) -> Vec<TokenEstimate> {
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let prefix = prefix_bytes(history);
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(0..=history.len())
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.map(|idx| tokens_at(history, records, idx, &prefix))
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.collect()
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}
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/// Prune 射影（`ToolResult.content = None`）で節約されるトークン数の推定。
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///
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/// `indices` は [`llm_worker::prune::prunable_indices`] が返す候補列を
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/// 想定する。各候補の content バイト差分を合算し、usage 履歴由来の
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/// tokens/byte レートでトークン数に換算する。範囲を「丸ごと drop」する
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/// のではなく、item 自体（summary 等）は残したままの値を返す点が
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/// `tokens_at` ベースの計算と異なる。
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pub(crate) fn savings_for_prune_impl(
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history: &[Item],
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records: &[UsageRecord],
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indices: &[usize],
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) -> TokenEstimate {
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let removed_bytes: u64 = indices
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.iter()
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.filter_map(|&i| history.get(i))
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.map(tool_result_content_bytes)
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.sum();
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if removed_bytes == 0 {
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return TokenEstimate {
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tokens: 0,
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source: EstimateSource::Measured,
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};
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}
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if records.is_empty() {
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return TokenEstimate {
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tokens: removed_bytes / 4,
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source: EstimateSource::NoData,
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};
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}
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// 最新の measurement を使って tokens/byte を求め、バイト差分を換算する。
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// 実測値そのものではなく比率しか使わないので、history_len と
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// record.history_len が一致しなくても rate は正しい。
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let prefix = prefix_bytes(history);
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let last = records.last().expect("records non-empty");
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let ref_bytes = prefix[last.history_len.min(history.len())];
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if ref_bytes == 0 || last.input_total_tokens == 0 {
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return TokenEstimate {
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tokens: 0,
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source: EstimateSource::Extrapolated,
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};
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}
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let tokens =
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(removed_bytes as u128 * last.input_total_tokens as u128 / ref_bytes as u128) as u64;
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let source = if last.history_len == history.len() {
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EstimateSource::Measured
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} else {
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EstimateSource::Extrapolated
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};
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TokenEstimate { tokens, source }
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}
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// ── Pod に生やす公開 API ───────────────────────────────────────────────
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impl<C: LlmClient, St: Store> Pod<C, St> {
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/// 現在の history 全体の推定トークン数。
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///
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/// 最後の measurement と、その後に追加された未測定分のバイト按分／外挿。
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pub fn total_tokens(&self) -> TokenEstimate {
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let usage = self.usage_history();
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llm_worker::token_counter::total_tokens(self.history(), &usage)
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}
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/// 任意の history index 時点でのプロンプト全長推定。
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///
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/// `total_tokens()` と同じ accounting を任意位置で評価する版。
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/// memory extract trigger が
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/// `total_tokens_at(now) - total_tokens_at(pointer)` で
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/// pointer 以降に増えたプロンプト長を測るのに使う。
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pub fn total_tokens_at(&self, history_len: usize) -> TokenEstimate {
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let usage = self.usage_history();
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llm_worker::token_counter::total_tokens_at(self.history(), &usage, history_len)
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}
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/// 末尾から `retained` トークン以上を残すための分割位置。
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///
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/// `history[..cut.index]` が要約／破棄される側、`history[cut.index..]` が残る側。
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pub fn split_for_retained(&self, retained: u64) -> SplitPoint {
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let usage = self.usage_history();
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split_for_retained_impl(self.history(), &usage, retained)
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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fn msg(text: &str) -> Item {
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Item::user_message(text)
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}
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fn record(history_len: usize, tokens: u64) -> UsageRecord {
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UsageRecord {
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history_len,
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input_total_tokens: tokens,
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cache_read_tokens: 0,
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cache_write_tokens: 0,
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output_tokens: 0,
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}
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}
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#[test]
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fn split_returns_zero_when_current_below_retained() {
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let history = vec![msg("a"), msg("b")];
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let records = vec![record(2, 50)];
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let cut = split_for_retained_impl(&history, &records, 1000);
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assert_eq!(cut.index, 0);
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}
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#[test]
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fn split_uses_current_occupancy_as_raw_byte_rate() {
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// Compact retained split does not treat the intermediate record at
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// len=2 as a raw prefix boundary. It uses the current occupancy
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// estimate (len=4 → 300) as a serialized-byte rate and keeps the
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// smallest item-granular suffix whose raw size covers retained=200.
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let history = vec![msg("a"), msg("b"), msg("c"), msg("d")];
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let records = vec![record(2, 100), record(4, 300)];
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let cut = split_for_retained_impl(&history, &records, 200);
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assert_eq!(cut.index, 1);
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assert_eq!(cut.source, EstimateSource::Measured);
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}
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#[test]
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fn split_does_not_use_non_current_measurements_as_cut_boundaries() {
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let history = vec![msg("aaaaaa"), msg("bbbbbb"), msg("cccccc"), msg("dddddd")];
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let records = vec![record(1, 50), record(4, 400)];
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let cut = split_for_retained_impl(&history, &records, 250);
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assert_eq!(cut.index, 1);
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assert_eq!(cut.source, EstimateSource::Measured);
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}
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#[test]
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fn split_ignores_non_monotonic_usage_spike_for_retained_tail() {
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let history: Vec<Item> = (0..20)
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.map(|idx| msg(&format!("message-{idx}-{}", "x".repeat(100))))
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.collect();
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let records = vec![
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record(2, 900), // request-time spike after pruning/projection
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record(20, 1000),
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];
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let cut = split_for_retained_impl(&history, &records, 100);
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// The old prefix-crossing logic picked index 2 because 900 >=
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// 1000-100, retaining almost the whole persisted history. The compact
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// split must instead use raw suffix size and keep only the tail needed
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// for the retained budget.
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assert!(cut.index > 10, "cut.index = {}", cut.index);
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assert_eq!(cut.source, EstimateSource::Measured);
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}
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#[test]
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fn split_all_when_retained_zero() {
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let history = vec![msg("a"), msg("b")];
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let records = vec![record(2, 100)];
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let cut = split_for_retained_impl(&history, &records, 0);
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assert_eq!(cut.index, 2);
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}
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fn tool_result_with(summary: &str, content: Option<&str>) -> Item {
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match content {
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Some(c) => Item::tool_result_with_content("call", summary, c),
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None => Item::tool_result("call", summary),
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}
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}
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#[test]
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fn token_estimates_for_prune_returns_every_prefix_boundary() {
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let history = vec![msg("a"), msg("b"), msg("c")];
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let estimates = token_estimates_for_prune_impl(&history, &[record(3, 300)]);
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assert_eq!(estimates.len(), history.len() + 1);
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assert_eq!(estimates[0].tokens, 0);
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assert_eq!(estimates[3].tokens, 300);
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assert_eq!(estimates[3].source, EstimateSource::Measured);
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}
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#[test]
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fn token_estimates_for_prune_propagates_no_data() {
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let history = vec![msg("a"), msg("b")];
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let estimates = token_estimates_for_prune_impl(&history, &[]);
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assert_eq!(estimates.len(), history.len() + 1);
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assert_eq!(estimates[0].source, EstimateSource::Measured);
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assert_eq!(estimates[1].source, EstimateSource::NoData);
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assert_eq!(estimates[2].source, EstimateSource::NoData);
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}
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#[test]
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fn savings_for_prune_skips_non_toolresult_indices() {
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let history = vec![msg("a"), msg("b"), msg("c")];
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// indices point at plain messages, not ToolResult → 0 savings.
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let est = savings_for_prune_impl(&history, &[record(3, 300)], &[0, 1, 2]);
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assert_eq!(est.tokens, 0);
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}
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#[test]
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fn savings_for_prune_skips_content_none_items() {
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let history = vec![
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msg("user"),
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tool_result_with("s1", None),
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tool_result_with("s2", None),
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];
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let est = savings_for_prune_impl(&history, &[record(3, 300)], &[1, 2]);
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assert_eq!(est.tokens, 0);
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}
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#[test]
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fn savings_for_prune_counts_only_content_delta() {
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// 1 item with big content vs the same structure without content.
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let big = "x".repeat(400);
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let history = vec![
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msg("user"),
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tool_result_with("summary", Some(&big)),
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msg("tail"),
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];
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// 1 record at end so rate = tokens / total_bytes
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let total_bytes: u64 = history.iter().map(item_bytes).sum();
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let records = vec![record(history.len(), total_bytes)]; // rate = 1 tok/byte
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let est = savings_for_prune_impl(&history, &records, &[1]);
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// saved bytes ≈ size of the big content payload; with rate=1 it
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// should be close to 400 and far from the full item bytes.
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let full_item_bytes = item_bytes(&history[1]);
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assert!(est.tokens > 0);
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assert!(est.tokens < full_item_bytes);
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assert!(est.tokens >= 400);
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assert_eq!(est.source, EstimateSource::Measured);
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}
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#[test]
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fn savings_for_prune_no_records_falls_back_to_bytes() {
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let history = vec![msg("u"), tool_result_with("s", Some("hello world"))];
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let est = savings_for_prune_impl(&history, &[], &[1]);
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assert_eq!(est.source, EstimateSource::NoData);
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assert!(est.tokens > 0);
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}
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#[test]
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fn savings_for_prune_extrapolated_when_history_grew_past_measurement() {
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let big = "x".repeat(200);
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let history = vec![
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msg("u1"),
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tool_result_with("s", Some(&big)),
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msg("u2"), // added after the last measurement
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];
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let records = vec![record(2, 100)];
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let est = savings_for_prune_impl(&history, &records, &[1]);
|
||
assert_eq!(est.source, EstimateSource::Extrapolated);
|
||
assert!(est.tokens > 0);
|
||
}
|
||
|
||
#[test]
|
||
fn savings_for_prune_empty_indices_is_zero() {
|
||
let history = vec![msg("a")];
|
||
let est = savings_for_prune_impl(&history, &[record(1, 100)], &[]);
|
||
assert_eq!(est.tokens, 0);
|
||
}
|
||
|
||
#[test]
|
||
fn savings_for_prune_ignores_out_of_range_indices() {
|
||
let history = vec![msg("a")];
|
||
let est = savings_for_prune_impl(&history, &[record(1, 100)], &[99]);
|
||
assert_eq!(est.tokens, 0);
|
||
}
|
||
|
||
fn tc(call_id: &str) -> Item {
|
||
Item::tool_call(call_id, "Read", "{}")
|
||
}
|
||
|
||
fn tr(call_id: &str) -> Item {
|
||
Item::tool_result(call_id, "summary")
|
||
}
|
||
|
||
#[test]
|
||
fn balance_noop_on_clean_message_boundary() {
|
||
let history = vec![msg("a"), msg("b"), msg("c")];
|
||
assert_eq!(balance_to_pair_boundary(&history, 2), 2);
|
||
assert_eq!(balance_to_pair_boundary(&history, 0), 0);
|
||
assert_eq!(balance_to_pair_boundary(&history, 3), 3);
|
||
}
|
||
|
||
#[test]
|
||
fn balance_retreats_from_inside_parallel_tool_results() {
|
||
// [Msg, TC_a, TC_b, TC_c, TR_a, TR_b, TR_c]
|
||
// cut=5 → retained=[TR_b, TR_c]。TR_c の TC は idx=3、TR_b は idx=2 →
|
||
// idx=2 まで後退。だが retained に TR_a (idx=4) が新たに入り、その TC_a
|
||
// は idx=1 でまだ外 → 連鎖後退で最終的に idx=1。retained は
|
||
// [TC_a, TC_b, TC_c, TR_a, TR_b, TR_c]。
|
||
let history = vec![
|
||
msg("u"),
|
||
tc("a"),
|
||
tc("b"),
|
||
tc("c"),
|
||
tr("a"),
|
||
tr("b"),
|
||
tr("c"),
|
||
];
|
||
assert_eq!(balance_to_pair_boundary(&history, 5), 1);
|
||
}
|
||
|
||
#[test]
|
||
fn balance_retreats_between_call_and_result() {
|
||
// [TC_a, TR_a, TC_b, TR_b]。cut=3 → retained=[TR_b] orphan。
|
||
// TC_b は idx=2 → cut=2。retained=[TC_b, TR_b]。
|
||
let history = vec![tc("a"), tr("a"), tc("b"), tr("b")];
|
||
assert_eq!(balance_to_pair_boundary(&history, 3), 2);
|
||
}
|
||
|
||
#[test]
|
||
fn balance_cascades_through_nested_pairs() {
|
||
// [TC_a, TC_b, TR_b, TR_a, TC_c, TR_c]。cut=3 → retained=[TR_a, TC_c, TR_c]。
|
||
// TR_a の TC は idx=0 → cut=0。retained=full。
|
||
let history = vec![tc("a"), tc("b"), tr("b"), tr("a"), tc("c"), tr("c")];
|
||
assert_eq!(balance_to_pair_boundary(&history, 3), 0);
|
||
}
|
||
|
||
#[test]
|
||
fn balance_noop_when_cut_at_pair_boundary() {
|
||
// [TC_a, TR_a, Msg, TC_b, TR_b]。cut=2 → retained=[Msg, TC_b, TR_b] balanced。
|
||
let history = vec![tc("a"), tr("a"), msg("u"), tc("b"), tr("b")];
|
||
assert_eq!(balance_to_pair_boundary(&history, 2), 2);
|
||
}
|
||
|
||
#[test]
|
||
fn balance_handles_orphan_result_without_matching_call() {
|
||
// ToolCall がそもそも存在しない ToolResult は触らない（壊れた history は
|
||
// ここでは直しようがない）。cut=1 → そのまま 1 を返す。
|
||
let history = vec![msg("u"), tr("zombie")];
|
||
assert_eq!(balance_to_pair_boundary(&history, 1), 1);
|
||
}
|
||
|
||
#[test]
|
||
fn balance_keeps_cut_when_call_is_inside_retained() {
|
||
// [Msg, TC_a, TR_a]。cut=1 → retained=[TC_a, TR_a]。TR_a の call_pos=1 >= idx=1。OK。
|
||
let history = vec![msg("u"), tc("a"), tr("a")];
|
||
assert_eq!(balance_to_pair_boundary(&history, 1), 1);
|
||
}
|
||
|
||
#[test]
|
||
fn split_for_retained_aligns_to_pair_boundary() {
|
||
// 並列 TC*3 / TR*3 ターン後に Msg を 1 件足し、retained=Msg のサイズ相当に
|
||
// 設定。トークン的には cut=末尾近くだが、orphan を避けるため TC 群の手前
|
||
// まで後退するはず。
|
||
let history = vec![
|
||
msg("user"),
|
||
tc("a"),
|
||
tc("b"),
|
||
tc("c"),
|
||
tr("a"),
|
||
tr("b"),
|
||
tr("c"),
|
||
msg("tail"),
|
||
];
|
||
let total_bytes: u64 = history.iter().map(item_bytes).sum();
|
||
let records = vec![record(history.len(), total_bytes)]; // rate = 1 tok/byte
|
||
// tail の item_bytes 相当のみ retain したい。
|
||
let tail_tokens = item_bytes(&history[7]);
|
||
let cut = split_for_retained_impl(&history, &records, tail_tokens);
|
||
// token 単独だと cut は 7（tail のみ retained）になるが、retained 先頭が
|
||
// Msg なら balance しなくて OK。balance helper の no-op を確認する意味も込めて
|
||
// index == 7 を期待する。
|
||
assert_eq!(cut.index, 7);
|
||
|
||
// 逆に retained をやや増やしてトークン的に cut=6（TR_c のみ retained）に
|
||
// させると、TR_c は orphan なので balance が 1 まで後退するはず。
|
||
let big_retain = tail_tokens + item_bytes(&history[6]);
|
||
let cut = split_for_retained_impl(&history, &records, big_retain);
|
||
assert_eq!(cut.index, 1);
|
||
}
|
||
}
|