Build tags, docs.

Author: ncruces

.github/workflows/go.yml

@@ -47,8 +47,12 @@ jobs:
     - name: Test
       run: go test -v ./...
 
+    - name: Test no locks
+      run: go test -v -tags sqlite3_nolock .
+      if: matrix.os == 'ubuntu-latest'
+
     - name: Test BSD locks
-      run: go test -v -tags sqlite3_bsd ./...
+      run: go test -v -tags sqlite3_flock ./...
       if: matrix.os == 'macos-latest'
 
     - name: Coverage report
@@ -58,6 +62,6 @@ jobs:
         amend: 'true'
         reuse-go: 'true'
       if: |
-        matrix.os == 'ubuntu-latest' &&
-        github.event_name == 'push'
+        github.event_name == 'push' &&
+        matrix.os == 'ubuntu-latest'
       continue-on-error: true

README.md

@@ -57,29 +57,25 @@ On Linux, macOS and illumos, this module uses
 to synchronize access to database files.
 OFD locks are fully compatible with process-associated POSIX advisory locks.
 
-On BSD Unixes, this module uses
+On BSD Unixes, this module may use
 [BSD locks](https://man.freebsd.org/cgi/man.cgi?query=flock&sektion=2).
-BSD locks may _not_ be compatible with process-associated POSIX advisory locks
-(they are on FreeBSD).
+BSD locks may _not_ be compatible with process-associated POSIX advisory locks.
 
 ##### TL;DR
 
 In all platforms for which this package builds,
-it is safe to use it to access databases concurrently from multiple goroutines.
-
-Additionally, on Windows, Linux, macOS, illumos and FreeBSD,
-it is _also_ safe to use it to access databases concurrently
+it should be safe to use it to access databases concurrently,
+from multiple goroutines, processes, and
 with _other_ implementations of SQLite.
 
-On other BSDs, where this might be unsafe,
-[this test](vfs/lock_test.go) should fail.
+If the package does not build for your platform,
+see [this](vfs/README.md#portability).
 
 #### Testing
 
 The pure Go VFS is tested by running SQLite's
 [mptest](https://github.com/sqlite/sqlite/blob/master/mptest/mptest.c)
-on Linux, macOS and Windows;
-BSD code paths are tested on macOS using the `sqlite3_bsd` build tag.
+on Linux, macOS and Windows.
 Performance is tested by running
 [speedtest1](https://github.com/sqlite/sqlite/blob/master/test/speedtest1.c).
 

vfs/README.md

@@ -2,8 +2,30 @@
 
 This package implements the SQLite [OS Interface](https://www.sqlite.org/vfs.html) (aka VFS).
 
-It replaces the default VFS with a pure Go implementation,
-that is tested on Linux, macOS and Windows,
-but which should also work on illumos and the various BSDs.
+It replaces the default SQLite VFS with a pure Go implementation.
 
-It also exposes interfaces that should allow you to implement your own custom VFSes.
+It also exposes interfaces that should allow you to implement your own custom VFSes.
+
+## Portability
+
+This package is tested on Linux, macOS and Windows,
+but it should also work on FreeBSD and illumos
+(code paths for those plaforms are tested on macOS and Linux, respectively).
+
+In all platforms for which this package builds,
+it should be safe to use it to access databases concurrently,
+from multiple goroutines, processes, and
+with _other_ implementations of SQLite.
+
+If the package does not build for your platform,
+you may try to use the `sqlite3_flock` and `sqlite3_nolock` build tags.
+These are only minimally tested and concurrency test failures should be expected.
+
+The `sqlite3_flock` tag uses
+[BSD locks](https://man.freebsd.org/cgi/man.cgi?query=flock&sektion=2).
+It should be safe to access databases concurrently from multiple goroutines and processes,
+but **not** with _other_ implementations of SQLite
+(_unless_ these are _also_ configured to use `flock`).
+
+The `sqlite3_nolock` tag uses no locking at all.
+Database corruption is the likely result from concurrent write access.

vfs/os_bsd.go

@@ -1,4 +1,4 @@
-//go:build freebsd || openbsd || netbsd || dragonfly || (darwin && sqlite3_bsd)
+//go:build sqlite3_flock || freebsd
 
 package vfs
 

vfs/os_darwin.go

@@ -1,4 +1,4 @@
-//go:build !sqlite3_bsd
+//go:build !sqlite3_flock
 
 package vfs
 

vfs/os_nolock.go

@@ -1,4 +1,4 @@
-//go:build sqlite3_nolock && solaris && !illumos
+//go:build sqlite3_nolock && unix && !(linux || darwin || freebsd || illumos)
 
 package vfs
 

vfs/os_ofd.go

@@ -1,4 +1,4 @@
-//go:build linux || illumos
+//go:build (linux || illumos) && !sqlite3_flock
 
 package vfs
 

vfs/os_std_alloc.go

@@ -1,4 +1,4 @@
-//go:build !linux && (!darwin || sqlite3_bsd)
+//go:build !linux && (!darwin || sqlite3_flock)
 
 package vfs
 

vfs/os_std_sync.go

@@ -1,4 +1,4 @@
-//go:build !linux && (!darwin || sqlite3_bsd)
+//go:build !linux && (!darwin || sqlite3_flock)
 
 package vfs