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LogDir::expire(): more intelligent removal of session dirs (MB #7708)

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The new algorithm is called after each sync, regardless whether that
succeeded or failed. The goal is to keep the number of session dirs
below maxLogDirs. If that is zero, all sessions are kept, as before.

The new algorithm will never:
- remove the last session, it is needed for reporting to the GUI
- remove the only session which has a dump of a specific source

Victims for removal are found by prioritizing all of them, evicting
oldest first in case of a bind. Sessions with database dumps are more
important than those without, sessions with changes (locally or on
server) more than those without changes, and finally sessions with
errors more than those without.

The useless INFO message about removing old sessions was removed. It
only confused users.
This commit is contained in:
Patrick Ohly 2010-02-18 15:31:29 +01:00
parent fecbb8c31e
commit 8220553d3b
1 changed files with 138 additions and 11 deletions
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149
src/syncevo/SyncContext.cpp
View file

@ -453,20 +453,127 @@ public:
return m_logfile;
}
// remove oldest backup dirs if exceeding limit
/**
* remove backup dir(s) if exceeding limit
*
* Assign a priority to each session dir, with lower
* meaning "less important". Then sort by priority and (if
* equal) creation time (aka index) in ascending
* order. The sessions at the beginning of the sorted
* vector are then removed first.
*
* DUMPS = any kind of database dump was made
* ERROR = session failed
* CHANGES = local data modified since previous dump (based on dumps
* of the current peer, for simplicity reasons),
* dump created for the first time,
* changes made during sync (detected with dumps and statistics)
*
* The goal is to preserve as many database dumps as possible
* and ideally those where something happened.
*
* Some criteria veto the removal of a session:
* - it is the only one holding a dump of a specific source
* - it is the last session
*/
void expire() {
if (m_logdir.size() && m_maxlogdirs > 0 ) {
vector<string> dirs;
getLogdirs(dirs);
/** stores priority and index in "dirs"; after sorting, delete from the start */
vector< pair<Priority, size_t> > victims;
/** maps from source name to list of information about dump, oldest first */
typedef map< string, list<DumpInfo> > Dumps_t;
Dumps_t dumps;
for (size_t i = 0;
i < dirs.size();
i++) {
bool changes = false;
bool havedumps = false;
bool errors = false;
LogDir logdir(m_client);
logdir.openLogdir(dirs[i]);
SyncReport report;
logdir.readReport(report);
SyncMLStatus status = report.getStatus();
if (status != STATUS_OK && status != STATUS_HTTP_OK) {
errors = true;
}
BOOST_FOREACH(SyncReport::SourceReport_t source, report) {
string &sourcename = source.first;
SyncSourceReport &sourcereport = source.second;
list<DumpInfo> &dumplist = dumps[sourcename];
if (sourcereport.m_backupBefore.isAvailable() ||
sourcereport.m_backupAfter.isAvailable()) {
// yes, we have backup dumps
havedumps = true;
DumpInfo info(i,
sourcereport.m_backupBefore.getNumItems(),
sourcereport.m_backupAfter.getNumItems());
// now check for changes, if none found yet
if (!changes) {
if (dumplist.empty()) {
// new backup dump
changes = true;
} else {
DumpInfo &previous = dumplist.back();
changes =
// item count changed -> items changed
previous.m_itemsDumpedAfter != info.m_itemsDumpedBefore ||
sourcereport.wasChanged(SyncSourceReport::ITEM_LOCAL) ||
sourcereport.wasChanged(SyncSourceReport::ITEM_REMOTE) ||
haveDifferentContent(sourcename,
dirs[previous.m_dirIndex], "after",
dirs[i], "before");
}
}
dumplist.push_back(info);
}
}
Priority pri =
havedumps ?
(changes ?
HAS_DUMPS_WITH_CHANGES :
errors ?
HAS_DUMPS_NO_CHANGES_WITH_ERRORS :
HAS_DUMPS_NO_CHANGES) :
(changes ?
NO_DUMPS_WITH_CHANGES :
errors ?
NO_DUMPS_WITH_ERRORS :
NO_DUMPS_NO_ERRORS);
victims.push_back(make_pair(pri, i));
}
sort(victims.begin(), victims.end());
int deleted = 0;
for (vector<string>::iterator it = dirs.begin();
it != dirs.end() && (int)dirs.size() - deleted > m_maxlogdirs;
++it, ++deleted) {
string &path = *it;
string msg = "removing " + path;
SE_LOG_INFO(NULL, NULL, "%s", msg.c_str());
rm_r(path);
for (size_t e = 0;
e < victims.size() && (int)dirs.size() - deleted > m_maxlogdirs;
++e) {
size_t index = victims[e].second;
string &path = dirs[index];
// preserve latest session
if (index != dirs.size() - 1) {
bool mustkeep = false;
// also check whether it holds the only backup of a source
BOOST_FOREACH(Dumps_t::value_type dump, dumps) {
if (dump.second.size() == 1 &&
dump.second.front().m_dirIndex == index) {
mustkeep = true;
break;
}
}
if (!mustkeep) {
SE_LOG_DEBUG(NULL, NULL, "removing %s", path.c_str());
rm_r(path);
++deleted;
}
}
}
}
}
@ -590,6 +697,28 @@ public:
}
private:
enum Priority {
NO_DUMPS_NO_ERRORS,
NO_DUMPS_WITH_ERRORS,
NO_DUMPS_WITH_CHANGES,
HAS_DUMPS_NO_CHANGES,
HAS_DUMPS_NO_CHANGES_WITH_ERRORS,
HAS_DUMPS_WITH_CHANGES
};
struct DumpInfo {
size_t m_dirIndex;
int m_itemsDumpedBefore;
int m_itemsDumpedAfter;
DumpInfo(size_t dirIndex,
int itemsDumpedBefore,
int itemsDumpedAfter) :
m_dirIndex(dirIndex),
m_itemsDumpedBefore(itemsDumpedBefore),
m_itemsDumpedAfter(itemsDumpedAfter)
{}
};
/**
* extract backup directory name from a full backup path
* for example, a full path "/home/xxx/.cache/syncevolution/default/funambol-2009-12-08-14-05"
@ -1157,9 +1286,7 @@ public:
"\nData modified locally during synchronization:\n",
"CLIENT_TEST_LEFT_NAME='before sync' CLIENT_TEST_RIGHT_NAME='after sync' CLIENT_TEST_REMOVED='removed during sync' CLIENT_TEST_ADDED='added during sync'");
if (status == STATUS_OK) {
m_logdir.expire();
}
m_logdir.expire();
}
}
}