lok: implement a joinThreads function - to wind down thread pools.

Necessary to do this before forking on Unix systems; use a
dynamic_cast interface since this is all for internal use.

Change-Id: I8a911322acd4ec5654eb0d14804c09d513a0bd4b
Signed-off-by: Michael Meeks <michael.meeks@collabora.com>
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/163335
Tested-by: Jenkins

3 files changed, 22 insertions, 1 deletions

diff --git a/include/LibreOfficeKit/LibreOfficeKit.h b/include/LibreOfficeKit/LibreOfficeKit.h
index 963d7962a6c2..78651128d3ac 100644
--- a/include/LibreOfficeKit/LibreOfficeKit.h
+++ b/include/LibreOfficeKit/LibreOfficeKit.h
@@ -140,6 +140,9 @@ struct _LibreOfficeKitClass
 
     /// @see lok::Office::stopURP
     void (*stopURP)(LibreOfficeKit* pThis, void* pSendURPToLOContext);
+
+    /// @see lok::Office::joinThreads
+    int (*joinThreads)(LibreOfficeKit* pThis);
 };
 
 #define LIBREOFFICEKIT_DOCUMENT_HAS(pDoc,member) LIBREOFFICEKIT_HAS_MEMBER(LibreOfficeKitDocumentClass,member,(pDoc)->pClass->nSize)
diff --git a/include/LibreOfficeKit/LibreOfficeKit.hxx b/include/LibreOfficeKit/LibreOfficeKit.hxx
index 29e644900caf..e94053378355 100644
--- a/include/LibreOfficeKit/LibreOfficeKit.hxx
+++ b/include/LibreOfficeKit/LibreOfficeKit.hxx
@@ -1051,7 +1051,6 @@ public:
      * @since LibreOffice 6.0
      * @param pURL macro url to run
      */
-
     bool runMacro( const char* pURL)
     {
         return mpThis->pClass->runMacro( mpThis, pURL );
@@ -1197,6 +1196,17 @@ public:
     {
         mpThis->pClass->stopURP(mpThis, pURPContext);
     }
+
+    /**
+     * Joins all threads if possible to get down to a single process
+     * which can be forked from safely.
+     *
+     * @returns non-zero for successful join, 0 for failure.
+     */
+    int joinThreads()
+    {
+        return mpThis->pClass->joinThreads(mpThis);
+    }
 };
 
 /// Factory method to create a lok::Office instance.
diff --git a/include/comphelper/lok.hxx b/include/comphelper/lok.hxx
index 545136f762ea..4ca03f049225 100644
--- a/include/comphelper/lok.hxx
+++ b/include/comphelper/lok.hxx
@@ -20,6 +20,14 @@ class LanguageTag;
 
 namespace comphelper::LibreOfficeKit
 {
+/// interface for allowing threads to be transiently shutdown.
+class COMPHELPER_DLLPUBLIC SAL_LOPLUGIN_ANNOTATE("crosscast") ThreadJoinable
+{
+public:
+    /// shutdown and join threads, @returns true on success
+    virtual bool joinThreads() = 0;
+};
+
 // Functions to be called only from the LibreOfficeKit implementation in desktop, not from other
 // places in LibreOffice code.