mesos git commit: Added a function to get the "Content-Length" field from HTTP header.

[be...@apache.org]

Repository: mesos
Updated Branches:
  refs/heads/master d4f6fde17 -> b9982ba8d


Added a function to get the "Content-Length" field from HTTP header.

Review: https://reviews.apache.org/r/30606


Project: http://git-wip-us.apache.org/repos/asf/mesos/repo
Commit: http://git-wip-us.apache.org/repos/asf/mesos/commit/b9982ba8
Tree: http://git-wip-us.apache.org/repos/asf/mesos/tree/b9982ba8
Diff: http://git-wip-us.apache.org/repos/asf/mesos/diff/b9982ba8

Branch: refs/heads/master
Commit: b9982ba8dfd98f48831da496d45a3fd0b4251c3e
Parents: d4f6fde
Author: Bernd Mathiske <be...@mesosphere.io>
Authored: Thu May 21 19:41:04 2015 -0700
Committer: Benjamin Hindman <be...@gmail.com>
Committed: Thu May 21 19:48:50 2015 -0700

----------------------------------------------------------------------
 .../3rdparty/stout/include/stout/net.hpp        | 69 +++++++++++++++++++-
 1 file changed, 68 insertions(+), 1 deletion(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/mesos/blob/b9982ba8/3rdparty/libprocess/3rdparty/stout/include/stout/net.hpp
----------------------------------------------------------------------
diff --git a/3rdparty/libprocess/3rdparty/stout/include/stout/net.hpp b/3rdparty/libprocess/3rdparty/stout/include/stout/net.hpp
index 0c09b34..a538fb1 100644
--- a/3rdparty/libprocess/3rdparty/stout/include/stout/net.hpp
+++ b/3rdparty/libprocess/3rdparty/stout/include/stout/net.hpp
@@ -84,11 +84,79 @@ inline struct sockaddr_storage createSockaddrStorage(const IP& ip, int port)
 }
 
 
+// Initializes libraries that net:: functions depend on, in a
+// thread-safe way. This does not have to be called explicitly by
+// the user of any functions in question. They will call this
+// themselves by need.
+inline void initialize()
+{
+  // We use a static struct variable to initialize in a thread-safe
+  // way, at least with respect to calls within net::*, since there
+  // is no way to guarantee that another library is not concurrently
+  // initializing CURL. Thread safety is provided by the fact that
+  // the value 'curl' should get constructed (i.e., the CURL
+  // constructor invoked) in a thread safe way (as of GCC 4.3 and
+  // required for C++11).
+  struct CURL
+  {
+    CURL()
+    {
+      // This is the only one function in libcurl that is not deemed
+      // thread-safe. (And it must be called at least once before any
+      // other libcurl function is used.)
+      curl_global_init(CURL_GLOBAL_ALL);
+    }
+  };
+
+  static CURL curl;
+}
+
+
+// Downloads the header of the specified HTTP URL with a HEAD request
+// and queries its "content-length" field. (Note that according to the
+// HTTP specification there is no guarantee that this field contains
+// any useful value.)
+inline Try<Bytes> contentLength(const std::string& url)
+{
+  initialize();
+
+  CURL* curl = curl_easy_init();
+  if (curl == NULL) {
+    curl_easy_cleanup(curl);
+    return Error("Failed to initialize libcurl");
+  }
+
+  curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
+  curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, true);
+  curl_easy_setopt(curl, CURLOPT_HEADER, 1);
+  curl_easy_setopt(curl, CURLOPT_NOBODY, 1);
+
+  CURLcode curlErrorCode = curl_easy_perform(curl);
+  if (curlErrorCode != 0) {
+    curl_easy_cleanup(curl);
+    return Error(curl_easy_strerror(curlErrorCode));
+  }
+
+  double result;
+  curl_easy_getinfo(curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &result);
+
+  curl_easy_cleanup(curl);
+
+  if (result < 0) {
+    return Error("No URL content-length available");
+  }
+
+  return Bytes(uint64_t(result));
+}
+
+
 // Returns the HTTP response code resulting from attempting to
 // download the specified HTTP or FTP URL into a file at the specified
 // path.
 inline Try<int> download(const std::string& url, const std::string& path)
 {
+  initialize();
+
   Try<int> fd = os::open(
       path,
       O_CREAT | O_WRONLY | O_CLOEXEC,
@@ -98,7 +166,6 @@ inline Try<int> download(const std::string& url, const std::string& path)
     return Error(fd.error());
   }
 
-  curl_global_init(CURL_GLOBAL_ALL);
   CURL* curl = curl_easy_init();
 
   if (curl == NULL) {