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Mass_parse: Fix caching behavior when multiple threads attempt to add same page

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This commit is contained in:
gnosygnu 2016-12-12 11:56:22 -05:00
parent f6b4d5f153
commit 317880d083
1 changed files with 14 additions and 15 deletions
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29
400_xowa/src/gplx/xowa/wikis/caches/Xow_page_cache.java
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@ -31,6 +31,13 @@ public class Xow_page_cache {
public void Add(byte[] ttl_full_db, Xow_page_cache_itm itm) {
cache.Add(ttl_full_db, itm);
}
private void Add_safe(byte[] ttl_full_db, Xow_page_cache_itm itm) {
synchronized (cache) { // LOCK:high-usage;DATE:2016-07-14
if (!cache.Has(ttl_full_db)) { // check again that itm is not in cache; note that this is necessary as cache.Get is not in "synchronized" block (for performance reasons); DATE:2016-12-12
cache.Add(ttl_full_db, itm);
}
}
}
public Xow_page_cache_itm Get_or_load_as_itm(Xoa_ttl ttl) {
byte[] ttl_full_db = ttl.Full_db();
Xow_page_cache_itm rv = (Xow_page_cache_itm)cache.Get_by(ttl_full_db);
@ -61,15 +68,11 @@ public class Xow_page_cache {
}
if (page_exists) {
rv = new Xow_page_cache_itm(false, page_ttl, page_text, page_redirect_from);
synchronized (this) { // LOCK:high-usage;DATE:2016-07-14
cache.Add(ttl_full_db, rv);
}
Add_safe(ttl_full_db, rv);
}
else {
synchronized (this) { // LOCK:high-usage;DATE:2016-07-14
cache.Add(ttl_full_db, Xow_page_cache_itm.Missing);
rv = null;
}
Add_safe(ttl_full_db, Xow_page_cache_itm.Missing);
rv = null;
}
return rv;
}
@ -82,21 +85,17 @@ public class Xow_page_cache {
if ( page.Db().Page().Exists() // page exists
|| page.Redirect_trail().Itms__len() > 0 ) { // page redirects to missing page; note that page.Missing == true and page.Redirected_src() != null; PAGE: en.w:Shah_Rukh_Khan; DATE:2016-05-02
rv = new Xow_page_cache_itm(false, page.Ttl(), page.Db().Text().Text_bry(), page.Redirect_trail().Itms__get_wtxt_at_0th_or_null());
synchronized (this) { // LOCK:high-usage;DATE:2016-07-14
cache.Add(ttl_full_db, rv);
}
Add_safe(ttl_full_db, rv);
}
else {
synchronized (this) { // LOCK:high-usage;DATE:2016-07-14
cache.Add(ttl_full_db, Xow_page_cache_itm.Missing);
rv = null;
}
Add_safe(ttl_full_db, Xow_page_cache_itm.Missing);
rv = null;
}
}
return rv;
}
public void Free_mem(boolean clear_permanent_itms) {
synchronized (this) { // LOCK:app-level; DATE:2016-07-06
synchronized (cache) { // LOCK:app-level; DATE:2016-07-06
if (clear_permanent_itms)
cache.Clear();
else {