Fix hang queue on open due to panic on atomic op

CHANGELOG.md

@@ -13,6 +13,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ### Removed
 
 ### Fixed
+- Panic on atomic operation (arm, x86-32) and File lock not released when panic occurs. PR #31
 
 ## [0.0.4]
 

file.go

@@ -36,6 +36,10 @@ import (
 // pages of type PageSize. Pages within the file are only accessible by page IDs
 // from within active transactions.
 type File struct {
+ // Atomic fields.
+ // Do not move: Must be 64bit-word aligned on some architectures.
+ txids uint64
+
  observer Observer
 
  path string
@@ -59,8 +63,6 @@ type File struct {
  metaActive int
 
  stats FileStats
-
- txids uint64
 }
 
 // internal contants
@@ -336,15 +338,25 @@ func (f *File) beginTx(settings TxOptions) (*Tx, reason) {
  }
 
  tracef("request new transaction (readonly: %v)\n", settings.Readonly)
+
+ // Acquire transaction log.
+ // Unlock on panic, so applications will not be blocked in case they try to
+ // defer some close operations on the file.
+ ok := false
  lock := f.locks.TxLock(settings.Readonly)
  lock.Lock()
- tracef("init new transaction (readonly: %v)\n", settings.Readonly)
+ defer cleanup.IfNot(&ok, lock.Unlock)
 
  txid := atomic.AddUint64(&f.txids, 1)
+
+ tracef("init new transaction (readonly: %v)\n", settings.Readonly)
+
  tx := newTx(f, txid, lock, settings)
  tracef("begin transaction: %p (readonly: %v)\n", tx, settings.Readonly)
 
  tx.onBegin()
+
+ ok = true
  return tx, nil
 }