From e4f0fa5db8622cc380df486094cffa1f26632904 Mon Sep 17 00:00:00 2001
From: Josh Yelon <jyelon@gmail.com>
Date: Fri, 6 Jul 2007 03:19:19 +0000
Subject: [PATCH] Added read-only flag

---
 panda/src/putil/bamCache.I   | 28 +++++++++++++++++++++++++++
 panda/src/putil/bamCache.cxx | 37 ++++++++++++++++++++++++++++++++----
 panda/src/putil/bamCache.h   |  8 +++++++-
 3 files changed, 68 insertions(+), 5 deletions(-)

diff --git a/panda/src/putil/bamCache.I b/panda/src/putil/bamCache.I
index 164b74ec5c..6f186dcf34 100644
--- a/panda/src/putil/bamCache.I
+++ b/panda/src/putil/bamCache.I
@@ -109,6 +109,34 @@ get_cache_max_kbytes() const {
   return _max_kbytes;
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: BamCache::set_read_only
+//       Access: Published
+//  Description: Can be used to put the cache in read-only mode,
+//               or take it out of read-only mode.  Note that if you
+//               put it into read-write mode, and it discovers that
+//               it does not have write access, it will put itself
+//               right back into read-only mode.
+////////////////////////////////////////////////////////////////////
+INLINE void BamCache::
+set_read_only(bool ro) {
+  _read_only = ro;
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: BamCache::get_read_only
+//       Access: Published
+//  Description: Returns true if the cache is in read-only mode.
+//               Normally, the cache starts in read-write mode.  It
+//               can put itself into read-only mode automatically if
+//               it discovers that it does not have write access to
+//               the cache.
+////////////////////////////////////////////////////////////////////
+INLINE bool BamCache::
+get_read_only() const {
+  return _read_only;
+}
+
 ////////////////////////////////////////////////////////////////////
 //     Function: BamCache::get_global_ptr
 //       Access: Published, Static
diff --git a/panda/src/putil/bamCache.cxx b/panda/src/putil/bamCache.cxx
index 2c798ecf8b..7f15017d64 100644
--- a/panda/src/putil/bamCache.cxx
+++ b/panda/src/putil/bamCache.cxx
@@ -39,7 +39,8 @@ BamCache::
 BamCache() :
   _active(true),
   _index(new BamCacheIndex),
-  _index_stale_since(0)
+  _index_stale_since(0),
+  _read_only(false)
 {
   ConfigVariableFilename model_cache_dir
     ("model-cache-dir", Filename(), 
@@ -182,6 +183,10 @@ store(BamCacheRecord *record) {
   nassertr(!record->_cache_pathname.empty(), false);
   nassertr(record->has_data(), false);
 
+  if (_read_only) {
+    return false;
+  }
+  
   consider_flush_index();
 
 #ifndef NDEBUG
@@ -206,6 +211,7 @@ store(BamCacheRecord *record) {
   if (!temp_pathname.open_write(temp_file)) {
     util_cat.error()
       << "Could not open cache file: " << temp_pathname << "\n";
+    emergency_read_only();
     return false;
   }
 
@@ -214,9 +220,10 @@ store(BamCacheRecord *record) {
     util_cat.error()
       << "Could not write cache file: " << temp_pathname << "\n";
     temp_pathname.unlink();
+    emergency_read_only();
     return false;
   }
-
+  
   if (!dout.write_header(_bam_header)) {
     util_cat.error()
       << "Unable to write to " << temp_pathname << "\n";
@@ -270,6 +277,22 @@ store(BamCacheRecord *record) {
   return true;
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: BamCache::emergency_read_only
+//       Access: Private
+//  Description: Called when an attempt to write to the cache dir
+//               has failed, usually for lack of disk space or 
+//               because of incorrect file permissions.  Outputs
+//               an error and puts the BamCache into read-only
+//               mode.
+////////////////////////////////////////////////////////////////////
+void BamCache::
+emergency_read_only() {
+  util_cat.error() <<
+    "Could not write to the Bam Cache.  Disabling future attempts.\n";
+  _read_only = true;
+}
+
 ////////////////////////////////////////////////////////////////////
 //     Function: BamCache::consider_flush_index
 //       Access: Published
@@ -299,9 +322,14 @@ flush_index() {
   }
 
   while (true) {
+    if (_read_only) {
+      return;
+    }
+
     Filename temp_pathname = Filename::temporary(_root, "index-", ".boo");
-    
+
     if (!do_write_index(temp_pathname, _index)) {
+      emergency_read_only();
       return;
     }
     
@@ -689,12 +717,13 @@ bool BamCache::
 do_write_index(Filename &index_pathname, const BamCacheIndex *index) {
   index_pathname.set_binary();
   ofstream index_file;
+  
   if (!index_pathname.open_write(index_file)) {
     util_cat.error()
       << "Could not open index file: " << index_pathname << "\n";
     return false;
   }
-
+  
   DatagramOutputFile dout;
   if (!dout.open(index_file)) {
     util_cat.error()
diff --git a/panda/src/putil/bamCache.h b/panda/src/putil/bamCache.h
index 82e0d87229..fbee1fb152 100644
--- a/panda/src/putil/bamCache.h
+++ b/panda/src/putil/bamCache.h
@@ -61,13 +61,16 @@ PUBLISHED:
   INLINE void set_cache_max_kbytes(int max_kbytes);
   INLINE int get_cache_max_kbytes() const;
 
+  INLINE void set_read_only(bool ro);
+  INLINE bool get_read_only() const;
+
   PT(BamCacheRecord) lookup(const Filename &source_filename, 
                             const string &cache_extension);
   bool store(BamCacheRecord *record);
 
   void consider_flush_index();
   void flush_index();
-
+  
   INLINE static BamCache *get_global_ptr();
 
 private:
@@ -83,6 +86,8 @@ private:
 
   void check_cache_size();
 
+  void emergency_read_only();
+  
   static BamCacheIndex *do_read_index(Filename &index_pathname);
   static bool do_write_index(Filename &index_pathname, const BamCacheIndex *index);
 
@@ -97,6 +102,7 @@ private:
   static void make_global();
 
   bool _active;
+  bool _read_only;
   Filename _root;
   int _flush_time;
   int _max_kbytes;