walletdb: Introduce AddRef and RemoveRef functions

achow101 · achow101 · commit 71d28e7cdca1 · 2020-07-14T11:07:16.000-04:00
Refactor mapFileUseCount increment and decrement to separate functions
AddRef and RemoveRef
diff --git a/src/wallet/bdb.cpp b/src/wallet/bdb.cpp
@@ -334,7 +334,7 @@ BerkeleyDatabase::~BerkeleyDatabase()
     }
 }
 
-BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode, bool fFlushOnCloseIn) : pdb(nullptr), activeTxn(nullptr), m_cursor(nullptr)
+BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode, bool fFlushOnCloseIn) : pdb(nullptr), activeTxn(nullptr), m_cursor(nullptr), m_database(database)
 {
     fReadOnly = (!strchr(pszMode, '+') && !strchr(pszMode, 'w'));
     fFlushOnClose = fFlushOnCloseIn;
@@ -408,7 +408,7 @@ BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode, bo
                 fReadOnly = fTmp;
             }
         }
-        ++env->mapFileUseCount[strFilename];
+        database.AddRef();
         strFile = strFilename;
     }
 }
@@ -446,11 +446,7 @@ void BerkeleyBatch::Close()
     if (fFlushOnClose)
         Flush();
 
-    {
-        LOCK(cs_db);
-        --env->mapFileUseCount[strFile];
-    }
-    env->m_db_in_use.notify_all();
+    m_database.RemoveRef();
 }
 
 void BerkeleyEnvironment::CloseDb(const std::string& strFile)
@@ -846,6 +842,21 @@ bool BerkeleyBatch::HasKey(CDataStream&& key)
     return ret == 0;
 }
 
+void BerkeleyDatabase::AddRef()
+{
+    LOCK(cs_db);
+    ++env->mapFileUseCount[strFile];
+}
+
+void BerkeleyDatabase::RemoveRef()
+{
+    {
+        LOCK(cs_db);
+        --env->mapFileUseCount[strFile];
+    }
+    env->m_db_in_use.notify_all();
+}
+
 std::unique_ptr<BerkeleyBatch> BerkeleyDatabase::MakeBatch(const char* mode, bool flush_on_close)
 {
     return MakeUnique<BerkeleyBatch>(*this, mode, flush_on_close);
diff --git a/src/wallet/bdb.h b/src/wallet/bdb.h
@@ -121,6 +121,11 @@ class BerkeleyDatabase
      */
     bool Rewrite(const char* pszSkip=nullptr);
 
+    /** Indicate the a new database user has began using the database. */
+    void AddRef();
+    /** Indicate that database user has stopped using the database and that it could be flushed or closed. */
+    void RemoveRef();
+
     /** Back up the entire database to a file.
      */
     bool Backup(const std::string& strDest) const;
@@ -212,6 +217,7 @@ class BerkeleyBatch : public DatabaseBatch
     bool fReadOnly;
     bool fFlushOnClose;
     BerkeleyEnvironment *env;
+    BerkeleyDatabase& m_database;
 
 public:
     explicit BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode = "r+", bool fFlushOnCloseIn=true);

Original file line number	Diff line number	Diff line change
`@@ -334,7 +334,7 @@ BerkeleyDatabase::~BerkeleyDatabase()`
`334`	`334`	`}`
`335`	`335`	`}`
`336`	`336`
`337`		`-BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode, bool fFlushOnCloseIn) : pdb(nullptr), activeTxn(nullptr), m_cursor(nullptr)`
	`337`	`+BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode, bool fFlushOnCloseIn) : pdb(nullptr), activeTxn(nullptr), m_cursor(nullptr), m_database(database)`
`338`	`338`	`{`
`339`	`339`	`fReadOnly = (!strchr(pszMode, '+') && !strchr(pszMode, 'w'));`
`340`	`340`	`fFlushOnClose = fFlushOnCloseIn;`
`@@ -408,7 +408,7 @@ BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode, bo`
`408`	`408`	`fReadOnly = fTmp;`
`409`	`409`	`}`
`410`	`410`	`}`
`411`		`- ++env->mapFileUseCount[strFilename];`
	`411`	`+ database.AddRef();`
`412`	`412`	`strFile = strFilename;`
`413`	`413`	`}`
`414`	`414`	`}`
`@@ -446,11 +446,7 @@ void BerkeleyBatch::Close()`
`446`	`446`	`if (fFlushOnClose)`
`447`	`447`	`Flush();`
`448`	`448`
`449`		`- {`
`450`		`- LOCK(cs_db);`
`451`		`- --env->mapFileUseCount[strFile];`
`452`		`- }`
`453`		`- env->m_db_in_use.notify_all();`
	`449`	`+ m_database.RemoveRef();`
`454`	`450`	`}`
`455`	`451`
`456`	`452`	`void BerkeleyEnvironment::CloseDb(const std::string& strFile)`
`@@ -846,6 +842,21 @@ bool BerkeleyBatch::HasKey(CDataStream&& key)`
`846`	`842`	`return ret == 0;`
`847`	`843`	`}`
`848`	`844`
	`845`	`+void BerkeleyDatabase::AddRef()`
	`846`	`+{`
	`847`	`+ LOCK(cs_db);`
	`848`	`+ ++env->mapFileUseCount[strFile];`
	`849`	`+}`
	`850`	`+`
	`851`	`+void BerkeleyDatabase::RemoveRef()`
	`852`	`+{`
	`853`	`+ {`
	`854`	`+ LOCK(cs_db);`
	`855`	`+ --env->mapFileUseCount[strFile];`
	`856`	`+ }`
	`857`	`+ env->m_db_in_use.notify_all();`
	`858`	`+}`
	`859`	`+`
`849`	`860`	`std::unique_ptr<BerkeleyBatch> BerkeleyDatabase::MakeBatch(const char* mode, bool flush_on_close)`
`850`	`861`	`{`
`851`	`862`	`return MakeUnique<BerkeleyBatch>(*this, mode, flush_on_close);`