make replays useful on BB

src/FileContentsCache.cc

@@ -8,36 +8,67 @@
 using namespace std;
 
 
+
+FileContentsCache::FileContentsCache(uint64_t ttl_usecs) : ttl_usecs(ttl_usecs) { }
+
 FileContentsCache::File::File(const string& name, shared_ptr<const string> contents,
     uint64_t load_time) : name(name), contents(contents), load_time(load_time) { }
 
-shared_ptr<const string> FileContentsCache::get(const std::string& name) {
-  return this->get(name, [name]() -> string { return load_file(name); });
-}
-
-shared_ptr<const string> FileContentsCache::get(const char* name) {
-  return this->get(string(name));
-}
-
-shared_ptr<const string> FileContentsCache::get(const std::string& name,
-    std::function<std::string()> generate) {
-  uint64_t t = now();
-  try {
-    auto& entry = this->name_to_file.at(name);
-    if (t - entry.load_time < 300000000) { // not 5 minutes old? return it
-      return entry.contents;
-    }
-  } catch (const out_of_range& e) { }
-
-  shared_ptr<const string> contents(new string(generate()));
-  this->name_to_file.erase(name);
-  this->name_to_file.emplace(piecewise_construct, forward_as_tuple(name),
+shared_ptr<const string> FileContentsCache::replace(
+    const string& name, string&& data, uint64_t t) {
+  if (t == 0) {
+    t = now();
+  }
+  shared_ptr<const string> contents(new string(move(data)));
+  auto emplace_ret = this->name_to_file.emplace(
+      piecewise_construct,
+      forward_as_tuple(name),
       forward_as_tuple(name, contents, t));
-
+  if (!emplace_ret.second) {
+    emplace_ret.first->second.contents = contents;
+    emplace_ret.first->second.load_time = t;
+  }
   return contents;
 }
 
-shared_ptr<const string> FileContentsCache::get(const char* name,
-    std::function<std::string()> generate) {
+shared_ptr<const string> FileContentsCache::replace(
+    const string& name, const void* data, size_t size, uint64_t t) {
+  string s(reinterpret_cast<const char*>(data), size);
+  return this->replace(name, move(s), t);
+}
+
+FileContentsCache::GetResult FileContentsCache::get_or_load(const std::string& name) {
+  return this->get(name, load_file);
+}
+
+FileContentsCache::GetResult FileContentsCache::get_or_load(const char* name) {
+  return this->get_or_load(string(name));
+}
+
+shared_ptr<const string> FileContentsCache::get_or_throw(const std::string& name) {
+  auto throw_fn = +[](const std::string&) -> string {
+    throw out_of_range("file missing from cache");
+  };
+  return this->get(name, throw_fn).data;
+}
+
+shared_ptr<const string> FileContentsCache::get_or_throw(const char* name) {
+  return this->get_or_throw(string(name));
+}
+
+FileContentsCache::GetResult FileContentsCache::get(const std::string& name,
+    std::function<std::string(const std::string&)> generate) {
+  uint64_t t = now();
+  try {
+    auto& entry = this->name_to_file.at(name);
+    if (this->ttl_usecs && (t - entry.load_time < this->ttl_usecs)) {
+      return {entry.contents, false};
+    }
+  } catch (const out_of_range& e) { }
+  return {this->replace(name, generate(name)), true};
+}
+
+FileContentsCache::GetResult FileContentsCache::get(const char* name,
+    std::function<std::string(const std::string&)> generate) {
   return this->get(string(name), generate);
 }