Method lookup

server/src/server/disk_prefix_cache.cpp:369–420

                scan_directory();
                return;
            }
            std::fclose(f);
        }
    }
}

// ─── Lookup ─────────────────────────────────────────────────────────────

bool DiskPrefixCache::lookup(const std::vector<int32_t> & prompt_ids, int slot) {
    if (disabled() || !layout_known_) return false;

    PrefixHash hash = hash_prefix(prompt_ids.data(), (int)prompt_ids.size());

    std::lock_guard<std::mutex> lock(mu_);
    int idx = find_entry(hash);
    if (idx < 0) return false;

    auto & entry = entries_[idx];
    if (!read_file(entry.path, slot)) {
        // File is corrupt or incompatible — remove it.
        std::fprintf(stderr, "[disk-cache] lookup failed, removing %s\n",
                     entry.path.c_str());
        std::remove(entry.path.c_str());
        total_bytes_ -= entry.file_size;
        entries_.erase(entries_.begin() + idx);
        return false;
    }

    if (layout_from_disk_) {
        const std::array<uint8_t, 16> disk_id = layout_id_;
        auto ref = backend_.snapshot_ref(slot);
        if (!ref.ctx) {
            backend_.snapshot_free(slot);
            return false;
        }
        compute_layout_id(ref.ctx);
        if (std::memcmp(disk_id.data(), layout_id_.data(), 16) != 0) {
            std::fprintf(stderr,
                         "[disk-cache] adopted layout mismatch: disk=%s model=%s\n",
                         hex(disk_id.data(), 16).c_str(),
                         hex(layout_id_.data(), 16).c_str());
            backend_.snapshot_free(slot);
            entries_.clear();
            total_bytes_ = 0;
            layout_from_disk_ = false;
            layout_dir_ = config_.cache_dir + "/" + hex(layout_id_.data(), 16);
            mkdir_p(layout_dir_);
            scan_directory();
            return false;
        }
        layout_from_disk_ = false;
        layout_dir_ = config_.cache_dir + "/" + hex(layout_id_.data(), 16);
    }

    // Update last_used on disk.