[GitHub] [trafficserver] serrislew commented on a diff in pull request #10147: Wasm plugin: Upgrade to the latest proxy-wasm-cpp-host and remove reference to WAVM

["serrislew (via GitHub)" <gi...@apache.org>]

serrislew commented on code in PR #10147:
URL: https://github.com/apache/trafficserver/pull/10147#discussion_r1286188921


##########
plugins/experimental/wasm/lib/src/wasm.cc:
##########
@@ -23,54 +23,75 @@
 #include <limits>
 #include <memory>
 #include <mutex>
+#include <queue>
 #include <string>
 #include <unordered_map>
 #include <utility>
 
-#include <openssl/sha.h>
-
 #include "include/proxy-wasm/bytecode_util.h"
 #include "include/proxy-wasm/signature_util.h"
 #include "include/proxy-wasm/vm_id_handle.h"
+#include "src/hash.h"
 
 namespace proxy_wasm {
 
 namespace {
 
-// Map from Wasm Key to the local Wasm instance.
+// Map from Wasm key to the thread-local Wasm instance.
 thread_local std::unordered_map<std::string, std::weak_ptr<WasmHandleBase>> local_wasms;
+// Wasm key queue to track stale entries in `local_wasms`.
+thread_local std::queue<std::string> local_wasms_keys;
+
+// Map from plugin key to the thread-local plugin instance.
 thread_local std::unordered_map<std::string, std::weak_ptr<PluginHandleBase>> local_plugins;
+// Plugin key queue to track stale entries in `local_plugins`.
+thread_local std::queue<std::string> local_plugins_keys;
+
+// Check no more than `MAX_LOCAL_CACHE_GC_CHUNK_SIZE` cache entries at a time during stale entries
+// cleanup.
+const size_t MAX_LOCAL_CACHE_GC_CHUNK_SIZE = 64;
+
 // Map from Wasm Key to the base Wasm instance, using a pointer to avoid the initialization fiasco.
 std::mutex base_wasms_mutex;
 std::unordered_map<std::string, std::weak_ptr<WasmHandleBase>> *base_wasms = nullptr;
 
-std::vector<uint8_t> Sha256(const std::vector<std::string_view> &parts) {
-  uint8_t sha256[SHA256_DIGEST_LENGTH];
-  SHA256_CTX sha_ctx;
-  SHA256_Init(&sha_ctx);
-  for (auto part : parts) {
-    SHA256_Update(&sha_ctx, part.data(), part.size());
-  }
-  SHA256_Final(sha256, &sha_ctx);
-  return std::vector<uint8_t>(std::begin(sha256), std::end(sha256));
+void cacheLocalWasm(const std::string &key, const std::shared_ptr<WasmHandleBase> &wasm_handle) {
+  local_wasms[key] = wasm_handle;
+  local_wasms_keys.emplace(key);
+}
+
+void cacheLocalPlugin(const std::string &key,
+                      const std::shared_ptr<PluginHandleBase> &plugin_handle) {
+  local_plugins[key] = plugin_handle;
+  local_plugins_keys.emplace(key);
 }
 
-std::string BytesToHex(const std::vector<uint8_t> &bytes) {
-  static const char *const hex = "0123456789ABCDEF";
-  std::string result;
-  result.reserve(bytes.size() * 2);
-  for (auto byte : bytes) {
-    result.push_back(hex[byte >> 4]);
-    result.push_back(hex[byte & 0xf]);
+template <class T>
+void removeStaleLocalCacheEntries(std::unordered_map<std::string, std::weak_ptr<T>> &cache,
+                                  std::queue<std::string> &keys) {
+  auto num_keys_to_check = std::min(MAX_LOCAL_CACHE_GC_CHUNK_SIZE, keys.size());
+  for (size_t i = 0; i < num_keys_to_check; i++) {
+    std::string key(keys.front());
+    keys.pop();
+
+    const auto it = cache.find(key);
+    if (it == cache.end()) {
+      continue;
+    }
+
+    if (it->second.expired()) {
+      cache.erase(it);
+    } else {
+      keys.push(std::move(key));
+    }
   }
-  return result;
 }
 
 } // namespace
 
 std::string makeVmKey(std::string_view vm_id, std::string_view vm_configuration,
                       std::string_view code) {
-  return BytesToHex(Sha256({vm_id, vm_configuration, code}));
+  return Sha256String({vm_id, "||", vm_configuration, "||", code});

Review Comment:
   Are these "| |" intentional to add to the hash key? Since it wasn't originally included? 



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