Merge pull request #904 from osschar/pfc-concurrent-ioactive-fix

[pfc] Fix crash when all remaining IO objects disconnect within a short time frame.
xrootd · Feb 6, 2019 · 442a084 · 442a084
2 parents 5cfa68a + d0fcbee
commit 442a084
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Showing 2 changed files with 19 additions and 4 deletions.
diff --git a/src/XrdFileCache/XrdFileCacheFile.cc b/src/XrdFileCache/XrdFileCacheFile.cc
@@ -60,6 +60,7 @@ File::File(const std::string& path, long long iOffset, long long iFileSize) :
    m_offset(iOffset),
    m_fileSize(iFileSize),
    m_current_io(m_io_map.end()),
+   m_ios_in_detach(0),
    m_non_flushed_cnt(0),
    m_in_sync(false),
    m_downloadCond(0),
@@ -143,14 +144,26 @@ bool File::ioActive(IO *io)
 
          // On last IO, consider write queue blocks. Note, this also contains
          // blocks being prefetched.
-         if (m_io_map.size() == 1)
+         // For multiple IOs the ioActive queries can occur in order before
+         // any of them are actually removed / detached.
+
+         bool io_active_result;
+
+         if (m_io_map.size() - m_ios_in_detach == 1)
          {
-            return ! m_block_map.empty();
+            io_active_result = ! m_block_map.empty();
          }
          else
          {
-            return mi->second.m_active_prefetches > 0;
+            io_active_result = mi->second.m_active_prefetches > 0;
+         }
+
+         if (io_active_result == false)
+         {
+            ++m_ios_in_detach;
          }
+
+         return io_active_result;
       }
       else
       {
@@ -239,6 +252,7 @@ void File::RemoveIO(IO *io)
       }
 
       m_io_map.erase(mi);
+      --m_ios_in_detach;
 
       if (m_io_map.empty() && m_prefetchState != kStopped && m_prefetchState != kComplete)
       {

diff --git a/src/XrdFileCache/XrdFileCacheFile.hh b/src/XrdFileCache/XrdFileCacheFile.hh
@@ -241,7 +241,8 @@ private:
    typedef IoMap_t::iterator        IoMap_i;
 
    IoMap_t    m_io_map;
-   IoMap_i    m_current_io; //!< IO object to be used for prefetching.
+   IoMap_i    m_current_io;     //!< IO object to be used for prefetching.
+   int        m_ios_in_detach;  //!< Number of IO objects to which we replied false to ioActive() and will be removed soon.
 
    // fsync
    std::vector<int>  m_writes_during_sync;