Introduce new account file structure.

This changes the locations that account files (wallet.bin, utxo.bin,
and tx.bin) are searched for when opening or disk syncing accounts.
Previously, files were saved in the following layout:

  ~/.btcwallet/
    - btcwallet/
      - wallet.bin
      - tx.bin
      - utxo.bin
    - btcwallet-AccountA/
      - wallet.bin
      - tx.bin
      - utxo.bin

This format had two issues.  First, each account would require its own
directory, causing a scalability issue on unix (and perhaps other)
platforms.  Second, there was no distinction between testnet and
mainnet wallets, and if mainnet support was enabled, btcwallet would
attempt to open accounts with testnet wallets.

Instead, the following file structure is now used:

  ~/.btcwallet/
    - testnet/
      - wallet.bin
      - tx.bin
      - utxo.bin
      - AccountA-wallet.bin
      - AccountA-tx.bin
      - AccountA-utxo.bin

This solves both of the previously-mentioned issues by requiring only
two subdirectories (one each for the testnet and mainnet bitcoin
networks), and by separating the locations to open and save testnet
and mainnet account files.

At startup, a check for the old account file structure is performed.
If found, files are moved to the new locations, and the old account
directories are removed.  Account files are moved to the testnet
directory, as only testnet support is currently enabled.

The version has been bumped to 0.1.1 to reflect this change.

Fixes #16.

disksync.go

@@ -34,6 +34,19 @@ var (
 	}
 )
 
+// accountFilename returns the filepath of an account file given the
+// filename suffix ("wallet.bin", "tx.bin", or "utxo.bin"), account
+// name and the network directory holding the file.
+func accountFilename(suffix, account, netdir string) string {
+	if account == "" {
+		// default account
+		return filepath.Join(netdir, suffix)
+	}
+
+	// non-default account
+	return filepath.Join(netdir, fmt.Sprintf("%v-%v", account, suffix))
+}
+
 // DirtyAccountSyncer synces dirty accounts for cases where the updated
 // information was not required to be immediately written to disk.  Accounts
 // may be added to dirtyAccounts and will be checked and processed every 10
@@ -63,20 +76,20 @@ func DirtyAccountSyncer() {
 
 // writeDirtyToDisk checks for the dirty flag on an account's wallet,
 // txstore, and utxostore, writing them to disk if any are dirty.
-func (w *Account) writeDirtyToDisk() error {
+func (a *Account) writeDirtyToDisk() error {
 	// Temporary files append the current time to the normal file name.
 	// In caes of failure, the most recent temporary file can be inspected
 	// for validity, and moved to replace the main file.
 	timeStr := fmt.Sprintf("%v", time.Now().Unix())
 
-	adir := w.accountdir(cfg)
-	if err := w.checkCreateAccountDir(adir); err != nil {
+	netdir := networkDir(cfg.Net())
+	if err := checkCreateDir(netdir); err != nil {
 		return err
 	}
 
-	wfilepath := filepath.Join(adir, "wallet.bin")
-	txfilepath := filepath.Join(adir, "tx.bin")
-	utxofilepath := filepath.Join(adir, "utxo.bin")
+	wfilepath := accountFilename("wallet.bin", a.name, netdir)
+	txfilepath := accountFilename("tx.bin", a.name, netdir)
+	utxofilepath := accountFilename("utxo.bin", a.name, netdir)
 
 	// UTXOs and transactions are synced to disk first.  This prevents
 	// any races from saving a wallet marked to be synced with block N
@@ -84,18 +97,18 @@ func (w *Account) writeDirtyToDisk() error {
 	// with block N-1.
 
 	// UTXOs
-	w.UtxoStore.RLock()
-	dirty := w.TxStore.dirty
-	w.UtxoStore.RUnlock()
+	a.UtxoStore.RLock()
+	dirty := a.TxStore.dirty
+	a.UtxoStore.RUnlock()
 	if dirty {
-		w.UtxoStore.Lock()
-		defer w.UtxoStore.Unlock()
+		a.UtxoStore.Lock()
+		defer a.UtxoStore.Unlock()
 		tmpfilepath := utxofilepath + "-" + timeStr
 		tmpfile, err := os.Create(tmpfilepath)
 		if err != nil {
 			return err
 		}
-		if _, err = w.UtxoStore.s.WriteTo(tmpfile); err != nil {
+		if _, err = a.UtxoStore.s.WriteTo(tmpfile); err != nil {
 			return err
 		}
 		tmpfile.Close()
@@ -106,22 +119,22 @@ func (w *Account) writeDirtyToDisk() error {
 			return err
 		}
 
-		w.UtxoStore.dirty = false
+		a.UtxoStore.dirty = false
 	}
 
 	// Transactions
-	w.TxStore.RLock()
-	dirty = w.TxStore.dirty
-	w.TxStore.RUnlock()
+	a.TxStore.RLock()
+	dirty = a.TxStore.dirty
+	a.TxStore.RUnlock()
 	if dirty {
-		w.TxStore.Lock()
-		defer w.TxStore.Unlock()
+		a.TxStore.Lock()
+		defer a.TxStore.Unlock()
 		tmpfilepath := txfilepath + "-" + timeStr
 		tmpfile, err := os.Create(tmpfilepath)
 		if err != nil {
 			return err
 		}
-		if _, err = w.TxStore.s.WriteTo(tmpfile); err != nil {
+		if _, err = a.TxStore.s.WriteTo(tmpfile); err != nil {
 			return err
 		}
 		tmpfile.Close()
@@ -132,22 +145,22 @@ func (w *Account) writeDirtyToDisk() error {
 			return err
 		}
 
-		w.TxStore.dirty = false
+		a.TxStore.dirty = false
 	}
 
 	// Wallet
-	w.mtx.RLock()
-	dirty = w.dirty
-	w.mtx.RUnlock()
+	a.mtx.RLock()
+	dirty = a.dirty
+	a.mtx.RUnlock()
 	if dirty {
-		w.mtx.Lock()
-		defer w.mtx.Unlock()
+		a.mtx.Lock()
+		defer a.mtx.Unlock()
 		tmpfilepath := wfilepath + "-" + timeStr
 		tmpfile, err := os.Create(tmpfilepath)
 		if err != nil {
 			return err
 		}
-		if _, err = w.WriteTo(tmpfile); err != nil {
+		if _, err = a.WriteTo(tmpfile); err != nil {
 			return err
 		}
 		tmpfile.Close()
@@ -158,7 +171,7 @@ func (w *Account) writeDirtyToDisk() error {
 			return err
 		}
 
-		w.dirty = false
+		a.dirty = false
 	}
 
 	return nil