[3/4] mesos git commit: Refactored fetcher cache directory creation.

[ji...@apache.org]

Refactored fetcher cache directory creation.

The fetcher's launcher creates the fetcher cache directory for each user
immediately before an artifact is fetched. In order to allow this
directory to be created by a different user than the user doing the
fetching, this patch factors out this directory creation and places it
before all fetches occur.

Review: https://reviews.apache.org/r/50199/


Project: http://git-wip-us.apache.org/repos/asf/mesos/repo
Commit: http://git-wip-us.apache.org/repos/asf/mesos/commit/a93b09bb
Tree: http://git-wip-us.apache.org/repos/asf/mesos/tree/a93b09bb
Diff: http://git-wip-us.apache.org/repos/asf/mesos/diff/a93b09bb

Branch: refs/heads/1.0.x
Commit: a93b09bbfddacb45f46e58aa0f42dc43ba06f49b
Parents: 34ba5f4
Author: Greg Mann <gr...@mesosphere.io>
Authored: Wed Jul 20 17:10:44 2016 -0700
Committer: Jie Yu <yu...@gmail.com>
Committed: Thu Jul 21 09:03:38 2016 -0700

----------------------------------------------------------------------
 src/launcher/fetcher.cpp | 54 ++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 48 insertions(+), 6 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/mesos/blob/a93b09bb/src/launcher/fetcher.cpp
----------------------------------------------------------------------
diff --git a/src/launcher/fetcher.cpp b/src/launcher/fetcher.cpp
index 0539b01..94b522d 100644
--- a/src/launcher/fetcher.cpp
+++ b/src/launcher/fetcher.cpp
@@ -378,15 +378,12 @@ static Try<string> fetchThroughCache(
   CHECK_NE(FetcherInfo::Item::BYPASS_CACHE, item.action())
     << "Unexpected fetcher action selector";
 
+  CHECK(os::exists(cacheDirectory.get()))
+    << "Fetcher cache directory was expected to exist but was not found";
+
   if (item.action() == FetcherInfo::Item::DOWNLOAD_AND_CACHE) {
     LOG(INFO) << "Downloading into cache";
 
-    Try<Nothing> mkdir = os::mkdir(cacheDirectory.get());
-    if (mkdir.isError()) {
-      return Error("Failed to create fetcher cache directory '" +
-                   cacheDirectory.get() + "': " + mkdir.error());
-    }
-
     Try<string> downloaded = download(
         item.uri().value(),
         path::join(cacheDirectory.get(), item.cache_filename()),
@@ -426,6 +423,45 @@ static Try<string> fetch(
 }
 
 
+// Checks to see if it's necessary to create a fetcher cache directory for this
+// user, and creates it if so.
+static Try<Nothing> createCacheDirectory(const FetcherInfo& fetcherInfo)
+{
+  if (!fetcherInfo.has_cache_directory()) {
+    return Nothing();
+  }
+
+  foreach (const FetcherInfo::Item& item, fetcherInfo.items()) {
+    if (item.action() != FetcherInfo::Item::BYPASS_CACHE) {
+      // If this user has fetched anything into the cache before, their cache
+      // directory will already exist. Set `recursive = true` when calling
+      // `os::mkdir` to ensure no error is returned in this case.
+      Try<Nothing> mkdir = os::mkdir(fetcherInfo.cache_directory(), true);
+      if (mkdir.isError()) {
+        return mkdir;
+      }
+
+      if (fetcherInfo.has_user()) {
+        // Fetching is performed as the task's user,
+        // so chown the cache directory.
+        Try<Nothing> chown = os::chown(
+            fetcherInfo.user(),
+            fetcherInfo.cache_directory(),
+            false);
+
+        if (chown.isError()) {
+          return chown;
+        }
+      }
+
+      break;
+    }
+  }
+
+  return Nothing();
+}
+
+
 // This "fetcher program" is invoked by the slave's fetcher actor
 // (Fetcher, FetcherProcess) to "fetch" URIs into the sandbox directory
 // of a given task. Its parameters are provided in the form of the env
@@ -473,6 +509,12 @@ int main(int argc, char* argv[])
 
   const string sandboxDirectory = fetcherInfo.get().sandbox_directory();
 
+  Try<Nothing> result = createCacheDirectory(fetcherInfo.get());
+  if (result.isError()) {
+    EXIT(EXIT_FAILURE)
+      << "Could not create the fetcher cache directory: " << result.error();
+  }
+
   const Option<string> cacheDirectory =
     fetcherInfo.get().has_cache_directory() ?
       Option<string>::some(fetcherInfo.get().cache_directory()) :