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CalDAV: more efficient "is empty" check (FDO #86335) 

Since 1.4.99.4, syncing WebDAV collections always checks first
whether there are items in the collections. This was partly done for
slow sync prevention (which is not necessary for empty collections),
partly for the "is the datastore usable" check.

However, this did not take into account that for CalDAV collections,
the entire content gets downloaded for this check. That is because
filtering by item type (VEVENT vs. VJOURNAL) is not implemented
correctly by all servers. So now all CalDAV syncs, whether incremental
or slow, always transfered all items, which is not the
intention (incremental syncs should be fast and efficient).

This commit adds a more efficient isEmpty() check: for simple CardDAV
collections, only luid and etag get transferred, as in
listAllItems(). This is the behavior from 1.5.

For CalDAV, a report with a filter for the content type is used and
the transfer gets aborted after the first item, without actually
double-checking the content of the item. This is different from
listAllItems(), which really transfers the content. This extra content
check would only be needed for some old servers (Radical 0.7) and is
not essential, because reporting "not empty" even when empty is safe.
This commit is contained in:
Patrick Ohly 2015-02-12 13:36:42 +01:00
parent 7e5638fd90
commit 75115022c5
1 changed files with 81 additions and 12 deletions
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93
src/backends/webdav/WebDAVSource.cpp
View File

@ -10,6 +10,7 @@
#include <boost/algorithm/string/classification.hpp>
#include <boost/algorithm/string/find.hpp>
#include <boost/scoped_ptr.hpp>
#include <boost/lambda/lambda.hpp>
#include <syncevo/LogRedirect.h>
#include <syncevo/IdentityProvider.h>
@ -1579,15 +1580,90 @@ void WebDAVSource::openPropCallback(Props_t &davProps,
}
}
static const ne_propname getetag[] = {
{ "DAV:", "getetag" },
{ "DAV:", "resourcetype" },
{ NULL, NULL }
};
static int FoundItem(bool &isEmpty,
const std::string &href,
const std::string &etag,
const std::string &status)
{
if (isEmpty) {
Neon::Status parsed;
// Err on the side of caution: if unsure about status, include item.
if (parsed.parse(status.c_str()) ||
parsed.klass == 2) {
isEmpty = false;
}
}
return isEmpty ? 0 : 100;
}
bool WebDAVSource::isEmpty()
{
contactServer();
// listing all items is relatively efficient, let's use that
// TODO: use truncated result search
RevisionMap_t revisions;
listAllItems(revisions);
return revisions.empty();
bool isEmpty;
if (!getContentMixed()) {
// Can use simple PROPFIND because we do not have to
// double-check that each item really contains the right data.
bool failed = false;
RevisionMap_t revisions;
Timespec deadline = createDeadline();
m_session->propfindURI(m_calendar.m_path, 1, getetag,
boost::bind(&WebDAVSource::listAllItemsCallback,
this, _1, _2, boost::ref(revisions),
boost::ref(failed)),
deadline);
if (failed) {
SE_THROW("incomplete listing of all items");
}
isEmpty = revisions.empty();
} else {
// Have to filter items on the server and set result to false
// when we get items back.
isEmpty = true;
const std::string query =
"<?xml version=\"1.0\" encoding=\"utf-8\" ?>\n"
"<C:calendar-query xmlns:D=\"DAV:\"\n"
"xmlns:C=\"urn:ietf:params:xml:ns:caldav\">\n"
"<D:prop>\n"
"<D:getetag/>\n"
"</D:prop>\n"
// Only get items of the right kind. In listAllItems() we
// don't trust the server to implement this correctly and
// double-check by downloading the data and looking into
// it, but here we are less concerned. It is less important
// to have reliable "is empty" information as long as we
// err on the side of returning "not empty" too often.
"<C:filter>\n"
"<C:comp-filter name=\"VCALENDAR\">\n"
"<C:comp-filter name=\"" + getContent() + "\">\n"
"</C:comp-filter>\n"
"</C:comp-filter>\n"
"</C:filter>\n"
"</C:calendar-query>\n";
Timespec deadline = createDeadline();
getSession()->startOperation("REPORT 'check for items'", deadline);
while (true) {
Neon::XMLParser parser;
parser.initAbortingReportParser(boost::bind(FoundItem,
boost::ref(isEmpty),
_1, _2, _3));
Neon::Request report(*getSession(), "REPORT", getCalendar().m_path, query, parser);
report.addHeader("Depth", "1");
report.addHeader("Content-Type", "application/xml; charset=\"utf-8\"");
if (getSession()->run(report, NULL, !boost::lambda::var(isEmpty))) {
break;
}
}
}
SE_LOG_DEBUG(getDisplayName(), "is %s", isEmpty ? "empty" : "not empty");
return isEmpty;
}
bool WebDAVSource::isUsable()
@ -1820,13 +1896,6 @@ std::string WebDAVSource::databaseRevision()
return ctag;
}
static const ne_propname getetag[] = {
{ "DAV:", "getetag" },
{ "DAV:", "resourcetype" },
{ NULL, NULL }
};
void WebDAVSource::listAllItems(RevisionMap_t &revisions)
{
contactServer();