Implemented basic corebill tracking.

src/util.cpp

@@ -40,6 +40,44 @@ bool rollover_hashset::try_emplace(const std::string hash)
     return false; // Hash already exists.
 }
 
+// ttl_set class methods.
+
+/**
+ * If key does not exist, inserts it with the specified ttl. If key exists,
+ * renews the expiration time to match the time-to-live from now onwards.
+ * @param key Object to insert.
+ * @param ttl Time to live in milliseonds.
+ */
+void ttl_set::emplace(const std::string key, uint64_t ttl_milli)
+{
+    ttlmap[key] = util::get_epoch_milliseconds() + ttl_milli;
+}
+
+void ttl_set::erase(const std::string &key)
+{
+    const auto itr = ttlmap.find(key);
+    if (itr != ttlmap.end())
+        ttlmap.erase(itr);
+}
+
+/**
+ * Returns true of the key exists and not expired. Returns false if key does not exist
+ * or has expired.
+ */
+bool ttl_set::exists(const std::string &key)
+{
+    const auto itr = ttlmap.find(key);
+    if (itr == ttlmap.end()) // Not found
+        return false;
+
+    // Check whether we are passed the expiration time (itr->second is the expiration time)
+    const bool expired = util::get_epoch_milliseconds() > itr->second;
+    if (expired)
+        ttlmap.erase(itr);
+
+    return !expired;
+}
+
 /**
  * Encodes provided bytes to hex string.
  * 
@@ -92,8 +130,8 @@ int hex2bin(unsigned char *decodedbuf, const size_t decodedbuf_len, std::string_
 int64_t get_epoch_milliseconds()
 {
     return std::chrono::duration_cast<std::chrono::milliseconds>(
-                  std::chrono::system_clock::now().time_since_epoch())
-                  .count();
+               std::chrono::system_clock::now().time_since_epoch())
+        .count();
 }
 
 /**