Gather balance info hashes into one struct guarded by an accessor...

Doing BalanceInfoDel in this delayed fashion will be needed when the other
call to it is eliminated, as shared_ptr simplifies the management of BlockFile
and makes the many calls to Ref and Deref disappear.

src/BlockFile.cpp

@@ -109,10 +109,15 @@ BlockFile::BlockFile(wxFileNameWrapper &&fileName, sampleCount samples):
    mSilentLog=FALSE;
 }
 
+// static
+unsigned long BlockFile::gBlockFileDestructionCount { 0 };
+
 BlockFile::~BlockFile()
 {
    if (!IsLocked() && mFileName.HasName())
       wxRemoveFile(mFileName.GetFullPath());
+
+   ++gBlockFileDestructionCount;
 }
 
 /// Returns the file name of the disk file associated with this

src/BlockFile.h

@@ -64,6 +64,8 @@ class PROFILE_DLL_API BlockFile /* not final, abstract */ {
    BlockFile(wxFileNameWrapper &&fileName, sampleCount samples);
    virtual ~BlockFile();
 
+   static unsigned long gBlockFileDestructionCount;
+
    // Reading
 
    /// Retrieves audio data from this BlockFile

src/DirManager.cpp

@@ -319,6 +319,8 @@ DirManager::DirManager()
 {
    wxLogDebug(wxT("DirManager: Created new instance."));
 
+   mLastBlockFileDestructionCount = BlockFile::gBlockFileDestructionCount;
+
    // Seed the random number generator.
    // this need not be strictly uniform or random, but it should give
    // unclustered numbers
@@ -347,8 +349,11 @@ DirManager::DirManager()
 
    // toplevel pool hash is fully populated to begin
    {
-      int i;
-      for(i=0; i< 256; i++) dirTopPool[i]=0;
+      // We can bypass the accessor function while initializing
+      auto &balanceInfo = mBalanceInfo;
+      auto &dirTopPool = balanceInfo.dirTopPool;
+      for(int i = 0; i < 256; ++i)
+         dirTopPool[i] = 0;
    }
 
    // Make sure there is plenty of space for temp files
@@ -650,6 +655,12 @@ int DirManager::BalanceMidAdd(int topnum, int midkey)
 {
    // enter the midlevel directory if it doesn't exist
 
+   auto &balanceInfo = GetBalanceInfo();
+   auto &dirMidPool = balanceInfo.dirMidPool;
+   auto &dirMidFull = balanceInfo.dirMidFull;
+   auto &dirTopPool = balanceInfo.dirTopPool;
+   auto &dirTopFull = balanceInfo.dirTopFull;
+
    if(dirMidPool.find(midkey) == dirMidPool.end() &&
          dirMidFull.find(midkey) == dirMidFull.end()){
       dirMidPool[midkey]=0;
@@ -668,6 +679,10 @@ int DirManager::BalanceMidAdd(int topnum, int midkey)
 
 void DirManager::BalanceFileAdd(int midkey)
 {
+   auto &balanceInfo = GetBalanceInfo();
+   auto &dirMidPool = balanceInfo.dirMidPool;
+   auto &dirMidFull = balanceInfo.dirMidFull;
+
    // increment the midlevel directory usage information
    if(dirMidPool.find(midkey) != dirMidPool.end()){
       dirMidPool[midkey]++;
@@ -700,11 +715,46 @@ void DirManager::BalanceInfoAdd(const wxString &file)
    }
 }
 
+auto DirManager::GetBalanceInfo() -> BalanceInfo &
+{
+   // Before returning the map,
+   // see whether any block files have disappeared,
+   // and if so update
+
+   auto count = BlockFile::gBlockFileDestructionCount;
+   if ( mLastBlockFileDestructionCount != count ) {
+      auto it = mBlockFileHash.begin(), end = mBlockFileHash.end();
+      while (it != end)
+      {
+         BlockFilePtr ptr { it->second };
+         if (!ptr) {
+            auto name = it->first;
+            mBlockFileHash.erase( it++ );
+            BalanceInfoDel( name );
+         }
+         else
+            ++it;
+      }
+   }
+
+   mLastBlockFileDestructionCount = count;
+
+   return mBalanceInfo;
+}
+
 // Note that this will try to clean up directories out from under even
 // locked blockfiles; this is actually harmless as the rmdir will fail
 // on non-empty directories.
 void DirManager::BalanceInfoDel(const wxString &file)
 {
+   // do not use GetBalanceInfo(),
+   // rather this function will be called from there.
+   auto &balanceInfo = mBalanceInfo;
+   auto &dirMidPool = balanceInfo.dirMidPool;
+   auto &dirMidFull = balanceInfo.dirMidFull;
+   auto &dirTopPool = balanceInfo.dirTopPool;
+   auto &dirTopFull = balanceInfo.dirTopFull;
+
    const wxChar *s=file.c_str();
    if(s[0]==wxT('e')){
       // this is one of the modern two-deep managed files
@@ -766,6 +816,11 @@ void DirManager::BalanceInfoDel(const wxString &file)
 // perform maintainence
 wxFileNameWrapper DirManager::MakeBlockFileName()
 {
+   auto &balanceInfo = GetBalanceInfo();
+   auto &dirMidPool = balanceInfo.dirMidPool;
+   auto &dirTopPool = balanceInfo.dirTopPool;
+   auto &dirTopFull = balanceInfo.dirTopFull;
+
    wxFileNameWrapper ret;
    wxString baseFileName;
 

src/DirManager.h

@@ -179,10 +179,19 @@ class PROFILE_DLL_API DirManager final : public XMLTagHandler {
    bool MoveOrCopyToNewProjectDirectory(BlockFile *f, bool copy);
 
    BlockHash mBlockFileHash; // repository for blockfiles
-   DirHash   dirTopPool;    // available toplevel dirs
-   DirHash   dirTopFull;    // full toplevel dirs
-   DirHash   dirMidPool;    // available two-level dirs
-   DirHash   dirMidFull;    // full two-level dirs
+
+   // Hashes for management of the sub-directory tree of _data
+   struct BalanceInfo
+   {
+      DirHash   dirTopPool;    // available toplevel dirs
+      DirHash   dirTopFull;    // full toplevel dirs
+      DirHash   dirMidPool;    // available two-level dirs
+      DirHash   dirMidFull;    // full two-level dirs
+   } mBalanceInfo;
+
+   // Accessor for the balance info, may need to do a delayed update for
+   // deletion in case other threads delete block files
+   BalanceInfo &GetBalanceInfo();
 
    void BalanceInfoDel(const wxString&);
    void BalanceInfoAdd(const wxString&);
@@ -204,6 +213,8 @@ class PROFILE_DLL_API DirManager final : public XMLTagHandler {
 
    sampleCount mMaxSamples; // max samples per block
 
+   unsigned long mLastBlockFileDestructionCount { 0 };
+
    static wxString globaltemp;
    wxString mytemp;
    static int numDirManagers;