From a5f2e260951edfea837c31bd615ee0cae543b75b Mon Sep 17 00:00:00 2001
From: "James E. Blair" <jeblair@redhat.com>
Date: Sun, 10 Feb 2019 10:04:44 -0800
Subject: [PATCH] Add LRU cache

---
 zuul-preview/main.cc | 66 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 64 insertions(+), 2 deletions(-)

diff --git a/zuul-preview/main.cc b/zuul-preview/main.cc
index fb497bf..be74564 100644
--- a/zuul-preview/main.cc
+++ b/zuul-preview/main.cc
@@ -20,6 +20,7 @@
 #include <config.h>
 #include <pthread.h>
 #include <cpprest/http_client.h>
+#include <bits/stdc++.h>
 
 using namespace std;
 
@@ -34,16 +35,73 @@ vector<string> split(const string &in)
   return parts;
 }
 
+class Cache {
+  list<pair<string, string>> queue;
+  unordered_map<string, list<pair<string, string>>::iterator> map;
+  uint size;
+
+public:
+  string notfound = "";
+
+  Cache(uint s)
+    : queue {}, map {}, size(0)
+  {
+    size = s;
+  }
+
+  string get(string key)
+  {
+    auto location = map.find(key);
+    if (location == map.end())
+      return notfound;
+
+    pair<string, string> val = *(location->second);
+    queue.erase(location->second);
+    queue.push_front(val);
+    cout << "get push " << val.second << endl;
+    return val.second;
+  }
+
+  void put(string key, string value)
+  {
+    auto location = map.find(key);
+    if (location != map.end())
+      return;
+
+    if (queue.size() == size) {
+      pair<string, string> last = queue.back();
+      cout << "put pop " << last.second << endl;
+      queue.pop_back();
+      map.erase(last.first);
+    }
+
+    cout << "put push " << value << endl;
+    queue.push_front(make_pair(key, value));
+    map[key] = queue.begin();
+  }
+};
+
+
 int main(int, char**)
 {
   web::http::client::http_client client("https://zuul.opendev.org");
 
   string hostname;
+  Cache cache = Cache(2);
   while (getline(cin, hostname)) {
     // Expected hostname:
     // site.75031cad206c4014ad7a3387091d15ab.openstack.preview.opendev.org
     // Apache will drop "preview.opendev.org", so our expected input will be:
     // site.75031cad206c4014ad7a3387091d15ab.openstack
+    // site.7c16d914db5a4c4b91cd9a31d119dd48.openstack
+    // site.688b70499b9a41a08f498ed6e932960c.openstack
+    // site.dbefc23dcc594577a8bfa4db4f9b0a8f.openstack
+
+    string val = cache.get(hostname);
+    if (val != cache.notfound) {
+      cout << val << endl;
+      continue;
+    }
 
     auto parts = split(hostname);
     if (parts.size() < 3) {
@@ -53,9 +111,11 @@ int main(int, char**)
     auto artifact = parts[0];
     auto buildid = parts[1];
     auto tenant = parts[2];
+    /*
     cout << artifact << endl
          << buildid << endl
          << tenant << endl;
+    */
 
      // 75031cad206c4014ad7a3387091d15ab
     auto uri = web::uri_builder("/api/tenant/" + tenant + "/build");
@@ -64,11 +124,13 @@ int main(int, char**)
         web::http::methods::GET, uri.to_string()).get();
     // body is a web::json::value
     auto body = response.extract_json().get();
-    cout << response.status_code() << endl;
-    cout << body.serialize() << endl;
+    //cout << response.status_code() << endl;
+    //cout << body.serialize() << endl;
 
     // TODO: use artifact
     // body["log_url"].as_string() returns a const std::string&
     cout << body["log_url"].as_string() << endl;
+
+    cache.put(hostname, body["log_url"].as_string());
   }
 }