[3/7] mesos git commit: Refactored 'MountInfoTable::read()' into two separate functions.

[ji...@apache.org]

Refactored 'MountInfoTable::read()' into two separate functions.

The original function now calls a helper which takes a string
representation of a 'MountInfoTable'. In a subsequent commit we will
use this helper to write more meaningful tests to stress the core
logic of the 'MountInfoTable::read()' functionality.

Review: https://reviews.apache.org/r/52704/


Project: http://git-wip-us.apache.org/repos/asf/mesos/repo
Commit: http://git-wip-us.apache.org/repos/asf/mesos/commit/44c43835
Tree: http://git-wip-us.apache.org/repos/asf/mesos/tree/44c43835
Diff: http://git-wip-us.apache.org/repos/asf/mesos/diff/44c43835

Branch: refs/heads/master
Commit: 44c438358def99d16024c1365355f01b80e4f66c
Parents: ccc746a
Author: Kevin Klues <kl...@gmail.com>
Authored: Wed Oct 12 22:34:12 2016 -0700
Committer: Jie Yu <yu...@gmail.com>
Committed: Wed Oct 12 22:34:12 2016 -0700

----------------------------------------------------------------------
 src/linux/fs.cpp | 35 +++++++++++++++++++++--------------
 src/linux/fs.hpp | 17 +++++++++++++++++
 2 files changed, 38 insertions(+), 14 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/mesos/blob/44c43835/src/linux/fs.cpp
----------------------------------------------------------------------
diff --git a/src/linux/fs.cpp b/src/linux/fs.cpp
index aeec882..f184d46 100644
--- a/src/linux/fs.cpp
+++ b/src/linux/fs.cpp
@@ -86,24 +86,13 @@ Try<bool> supported(const string& fsname)
   return false;
 }
 
-
 Try<MountInfoTable> MountInfoTable::read(
-    const Option<pid_t>& pid,
+    const string& lines,
     bool hierarchicalSort)
 {
   MountInfoTable table;
 
-  const string path = path::join(
-      "/proc",
-      (pid.isSome() ? stringify(pid.get()) : "self"),
-      "mountinfo");
-
-  Try<string> lines = os::read(path);
-  if (lines.isError()) {
-    return Error("Failed to read mountinfo file: " + lines.error());
-  }
-
-  foreach (const string& line, strings::tokenize(lines.get(), "\n")) {
+  foreach (const string& line, strings::tokenize(lines, "\n")) {
     Try<Entry> parse = MountInfoTable::Entry::parse(line);
     if (parse.isError()) {
       return Error("Failed to parse entry '" + line + "': " + parse.error());
@@ -140,7 +129,7 @@ Try<MountInfoTable> MountInfoTable::read(
     std::function<void(int)> sortFrom = [&](int parentId) {
       CHECK(!visitedParents.contains(parentId))
         << "Cycle found in mount table hierarchy at entry"
-        << " '" << stringify(parentId) << "': " << std::endl << lines.get();
+        << " '" << stringify(parentId) << "': " << std::endl << lines;
 
       visitedParents.insert(parentId);
 
@@ -172,6 +161,24 @@ Try<MountInfoTable> MountInfoTable::read(
 }
 
 
+Try<MountInfoTable> MountInfoTable::read(
+    const Option<pid_t>& pid,
+    bool hierarchicalSort)
+{
+  const string path = path::join(
+      "/proc",
+      (pid.isSome() ? stringify(pid.get()) : "self"),
+      "mountinfo");
+
+  Try<string> lines = os::read(path);
+  if (lines.isError()) {
+    return Error("Failed to read mountinfo file: " + lines.error());
+  }
+
+  return MountInfoTable::read(lines.get(), hierarchicalSort);
+}
+
+
 Try<MountInfoTable::Entry> MountInfoTable::Entry::parse(const string& s)
 {
   MountInfoTable::Entry entry;

http://git-wip-us.apache.org/repos/asf/mesos/blob/44c43835/src/linux/fs.hpp
----------------------------------------------------------------------
diff --git a/src/linux/fs.hpp b/src/linux/fs.hpp
index 090c826..da49c9e 100644
--- a/src/linux/fs.hpp
+++ b/src/linux/fs.hpp
@@ -222,6 +222,23 @@ struct MountInfoTable {
       const Option<pid_t>& pid = None(),
       bool hierarchicalSort = true);
 
+  // Read a mountinfo table from a string.
+  // @param   lines   The contents of a mountinfo table represented as
+  //                  a string. Different entries in the string are
+  //                  separated by a newline.
+  // @param   hierarchicalSort
+  //                  A boolean indicating whether the entries in the
+  //                  mountinfo table should be sorted according to
+  //                  their parent / child relationship (as opposed to
+  //                  the temporal ordering of when they were
+  //                  mounted). The two orderings may differ (for
+  //                  example) if a filesystem is remounted after some
+  //                  of its children have been mounted.
+  // @return  An instance of MountInfoTable if success.
+  static Try<MountInfoTable> read(
+      const std::string& lines,
+      bool hierarchicalSort = true);
+
   // TODO(jieyu): Introduce 'find' methods to find entries that match
   // the given conditions (e.g., target, root, devno, etc.).