# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1383322029 -3600
# Node ID 6ce8836f70752195591dbbec01a2a7192f923c36
# Parent  04eb43f3cd34d0dfaa3512a210492ac5723cb408
Added caching of PDF output by page revision and paper size.

diff -r 04eb43f3cd34 -r 6ce8836f7075 actions/ExportPDF.py
--- a/actions/ExportPDF.py	Fri Nov 01 15:21:36 2013 +0100
+++ b/actions/ExportPDF.py	Fri Nov 01 17:07:09 2013 +0100
@@ -6,7 +6,8 @@
     @license: GNU GPL (v2 or later), see COPYING.txt for details.
 """
 
-from MoinMoin.action import ActionBase
+from MoinMoin import caching
+from MoinMoin.action import ActionBase, cache
 from MoinMoin.wikiutil import escape
 from MoinSupport import ActionSupport, escattr, getFormatterClass, formatText, get_send_headers
 from os.path import join
@@ -147,18 +148,36 @@
 
         _ = self._
         form = self.get_form()
+        request = self.request
 
         paper_size = form.get("paper-size", [""])[0]
 
         if not paper_size in self._get_paper_sizes() or []:
             return 0, _("A paper size must be chosen.")
 
+        # See if the revision is cached.
+
+        cache_key = cache.key(request, content="%s-%s" % (self.page.rev, paper_size))
+        cache_entry = caching.CacheEntry(request, self.page, cache_key, scope="item")
+
+        # Open any available cache entry and read it.
+
+        if cache_entry.exists():
+            cache_entry.open()
+            try:
+                self._write_pdf(cache_entry.read())
+                return 1, None
+            finally:
+                cache_entry.close()
+
+        # Otherwise, prepare the PDF.
+
         if self.mode == "docbook":
-            return self._export_using_docbook(paper_size)
+            return self._export_using_docbook(paper_size, cache_entry)
         elif self.mode == "wkhtmltopdf":
-            return self._export_using_wkhtmltopdf(paper_size)
+            return self._export_using_wkhtmltopdf(paper_size, cache_entry)
         elif self.mode == "htmldoc":
-            return self._export_using_htmldoc(paper_size)
+            return self._export_using_htmldoc(paper_size, cache_entry)
         else:
             return 0, _("The action must be configured to use a particular PDF generation tool.")
 
@@ -233,7 +252,7 @@
         self._write_pdf(out)
         return 1, None
 
-    def _export_using_wkhtmltopdf(self, paper_size):
+    def _export_using_wkhtmltopdf(self, paper_size, cache_entry):
 
         """
         Send the page HTML to the processor, indicating the given 'paper_size'.
@@ -251,9 +270,9 @@
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE)
 
-        return self._write_pdf_for_html(p, self._get_page_as_html())
+        return self._write_pdf_for_html(p, self._get_page_as_html(), cache_entry)
 
-    def _export_using_htmldoc(self, paper_size):
+    def _export_using_htmldoc(self, paper_size, cache_entry):
 
         """
         Send the page HTML to the processor, indicating the given 'paper_size'.
@@ -272,9 +291,9 @@
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE)
 
-        return self._write_pdf_for_html(p, self._get_page_as_html())
+        return self._write_pdf_for_html(p, self._get_page_as_html(), cache_entry)
 
-    def _export_using_docbook(self, paper_size):
+    def _export_using_docbook(self, paper_size, cache_entry):
 
         """
         Send the page DocBook XML to the processor, indicating the given
@@ -320,10 +339,28 @@
         if retcode != 0:
             return 0, err
 
+        self._write_to_cache(out, cache_entry)
         self._write_pdf(out)
         return 1, None
 
+    def _write_to_cache(self, out, cache_entry):
+
+        "Write the output 'out' to the given 'cache_entry'."
+
+        cache_entry.open(mode="w")
+        try:
+            try:
+                cache_entry.write(out)
+            finally:
+                cache_entry.close()
+        except IOError:
+            if cache_entry.exists():
+                cache_entry.remove()
+
     def _write_pdf(self, out):
+
+        "Write the output 'out' to the request/response."
+
         request = self.request
 
         send_headers = get_send_headers(request)