Added informative message when Stackdump is disabled during a site import.

python/media/css/main.css

@@ -11,6 +11,11 @@ pre code {
     background-color: transparent;
 }
 
+h3, h4, h5, h6 {
+    line-height: normal;
+    margin-bottom: 0.5em;
+}
+
 /* don't want it to have a fixed position; so we'll override it */
 .topbar {
     position: absolute;
@@ -358,12 +363,12 @@ h1.answers {
     float: right;
 }
 
-.nodata.row {
+.nodata.row, .importinprogress.row {
     margin-top: 50px;
     margin-bottom: 20px;
 }
 
-.nodata h2 {
+.nodata h2, .importinprogress h2 {
     margin-top: 25px;
     margin-bottom: 7px;
 }
@@ -383,4 +388,8 @@ h1.answers {
 
 .nodata pre {
     margin-top: 7px;
+}
+
+.importinprogress .subinfo {
+    color: #999999;
 }

python/src/stackdump/app.py

@@ -237,6 +237,13 @@ def error500(error):
     ex = error.exception
     if isinstance(ex, NoSitesImportedError):
         return render_template('nodata.html')
+    if isinstance(ex, OperationalError):
+        # if the error is the database is locked, then it is likely that an
+        # import operation is in progress (for SQLite anyway). Return a nice
+        # error page for that.
+        # HACK: the exception object doesn't seem to provide a better way though.
+        if 'database is locked' in ex.args:
+            return render_template('importinprogress.html')
     
     # otherwise, return the standard error message
     return repr(error)
@@ -431,14 +438,11 @@ def get_sites():
     NoSitesImportedError. This error is designed to trigger the 500 error
     handler.
     '''
-    try:
-        sites = list(Site.select().orderBy('name'))
-        if len(sites) == 0:
-            raise NoSitesImportedError()
-        
-        return sites
-    except OperationalError as e:
-        raise NoSitesImportedError(e)
+    sites = list(Site.select().orderBy('name'))
+    if len(sites) == 0:
+        raise NoSitesImportedError()
+    
+    return sites
 
 def decode_json_fields(obj):
     '''\

python/src/stackdump/templates/importinprogress.html

@@ -0,0 +1,26 @@
+{% extends 'base.html' %}
+
+{% block title %}
+Stackdump // Site import in progress
+{% endblock %}
+
+{% block body %}
+    <div class="row importinprogress">
+        <div class="span16">
+            <h1>Stackdump is currently importing a StackExchange site.</h1>
+            <p>
+                Stackdump is temporarily disabled while a StackExchange site is
+                being imported. It will automatically become available again
+                once the import process has completed. This should take no
+                longer than 12 hours.
+            </p>
+            
+            <p class="subinfo">
+                If this message is appearing and no site is currently being
+                imported, then check the Stackdump web log and ensure Stackdump
+                has access to the configured database.
+            </p>
+            
+        </div>
+    </div>
+{% endblock %}