Finally implement correct positioning in the buffer to read next entry.

Solves problem with unclear way when to read or not to read version for
empty STL container.

Author: linev

changes.md

@@ -5,7 +5,8 @@
 2. Support TBranchObject - appears in old files
 3. Fix - problem with zooming in THStack
 4. Fix - empty baskets at the end of branch store
-5. Fix - more checks when reading version for empty STL container 
+5. Fix - solve problem with empty STL containers
+6. Fix - correcty set buffer position for the entry  
 
 
 ## Changes in 5.0.0

scripts/JSRootIOEvolution.js

@@ -1980,7 +1980,6 @@
             if ((element._typename === 'TStreamerSTLstring') ||
                 (member.typename == "string") || (member.typename == "string*")) {
                member.readelem = function(buf) { return buf.ReadTString(); };
-               // member.read_empty_stl_version = false;
             } else
             if ((stl === JSROOT.IO.kSTLvector) || (stl === JSROOT.IO.kSTLlist) ||
                 (stl === JSROOT.IO.kSTLdeque) || (stl === JSROOT.IO.kSTLset) ||
@@ -2030,11 +2029,6 @@
                         subelem.$fictional = true;
                         member.submember = JSROOT.IO.CreateMember(subelem, file);
                      }
-                     //else
-                     //if ((member.conttype.indexOf('pair<')===0) &&
-                     //   JSROOT.IO.GetPairStreamer(null, member.conttype, file))  {
-                     //     // member.read_empty_stl_version = true; // seems to be, pair<> needs empty version
-                     // }
                   }
                }
             } else
@@ -2051,8 +2045,6 @@
 
                member.streamer = JSROOT.IO.GetPairStreamer(member.si, member.pairtype, file);
 
-               // member.read_empty_stl_version = true; // in branch reading read version even for empty container, vector does not have it
-
                if (!member.streamer || (member.streamer.length!==2)) {
                   JSROOT.console('Fail to build streamer for pair ' + member.pairtype);
                   delete member.streamer;
@@ -2077,40 +2069,10 @@
             if (!element.$fictional) {
 
                member.read_version = function(buf, cnt) {
-                  // read version, check member-wise flag; if any, read version for contained object
-
-                  // console.log('start reading version', buf.o, buf.remain(), 'cnt', cnt, 'read_empty', this.read_empty_stl_version);
-
-                  // workaround - in some cases version is not written for empty container
-                  if ((cnt===0) && ((buf.remain()<6) || this.read_empty_stl_version === false))  {
-                     if (this.read_empty_stl_version) throw new Error("SKIP0 VERSION WHEN SHOULD READ " + this.typename + " - " + this.name);
-                     return null;
-                  }
 
+                  if (cnt===0) return null;
                   var o = buf.o, ver = buf.ReadVersion();
-
-                  console.log('cnt',cnt, 'ver', ver, 'read_empty', this.read_empty_stl_version);
-
                   this.member_wise = ((ver.val & JSROOT.IO.kStreamedMemberWise) !== 0);
-
-                  if ((cnt===0) && (ver.bytecnt===0) && !this.member_wise) {
-
-                     if (this.read_empty_stl_version!==true) throw new Error("READ ZERO WHEN SHOULD NOT " + this.typename + " - " + this.name + ' ver ' + ver.val);
-
-                     return ver;
-                  }
-
-                  // workaround - in some cases version is not written for empty container
-                  if (cnt===0)
-                     if (((ver.bytecnt!==6) && (ver.bytecnt!=2) && !this.read_empty_stl_version) ||
-                        (ver.bytecnt && (ver.bytecnt > (this.member_wise ? 12 : 6)))) {
-                        if (this.read_empty_stl_version) throw new Error("SKIP1 VERSION WHEN SHOULD READ " + this.typename + " - " + this.name + '  bytecnt ' + ver.bytecnt);
-                        buf.o = o;
-                        return null;
-                        }
-
-                  if ((cnt===0) && this.read_empty_stl_version===false) throw new Error("READ VERSION WHEN SHOULD SKIP " + this.typename + " - " + this.name);
-
                   this.stl_version = undefined;
                   if (this.member_wise) {
                      this.stl_version = { val: buf.ntoi2() };

scripts/JSRootTree.js

@@ -1409,7 +1409,6 @@
                staged_prev: 0, // entry limit of previous I/O request
                staged_now: 0, // entry limit of current I/O request
                progress_showtm: 0, // last time when progress was showed
-               have_to_read_empty_stl_branch: false, // by default splitted container branch read version if empty container
                GetBasketEntry : function(k) {
                   if (!this.branch || (k > this.branch.fMaxBaskets)) return 0;
                   var res = (k < this.branch.fMaxBaskets) ? this.branch.fBasketEntry[k] : 0;
@@ -1654,13 +1653,8 @@
           } else
           if (is_brelem && (nb_leaves <= 1)) {
 
-             item.have_to_read_empty_stl_branch = (branch.fType === JSROOT.BranchType.kClonesMemberNode);
-
              elem = JSROOT.IO.FindBrachStreamerElement(branch, handle.file);
 
-             if (elem)
-                console.log('ELEMENT', elem.fName, elem.fType, elem.fTypeName, 'READ_EMPTY', item.have_to_read_empty_stl_branch);
-
              // this is basic type - can try to solve problem differently
              if (!elem && branch.fStreamerType && (branch.fStreamerType < 20)) {
                 elem = JSROOT.IO.CreateStreamerElement(target_name, branch.fStreamerType);
@@ -1775,9 +1769,6 @@
              if (member.objs_branch_func) {
                 // STL branch provides special function for the reading
                 member.func = member.objs_branch_func;
-
-                member.read_empty_stl_version = item.have_to_read_empty_stl_branch;
-
              } else {
                 member.func0 = member.func;
 
@@ -1853,16 +1844,13 @@
                 // function provided by normal I/O
                 member.func = member.branch_func;
                 member.stl_size = item_cnt.name;
-                member.read_empty_stl_version = item.have_to_read_empty_stl_branch;
-
              } else
              if ((elem.fType === JSROOT.IO.kStreamLoop) || (elem.fType === JSROOT.IO.kOffsetL+JSROOT.IO.kStreamLoop)) {
                 if (item_cnt2) {
                    // special solution for kStreamLoop
                    member.stl_size = item_cnt.name;
                    member.cntname = item_cnt2.name;
                    member.func = member.branch_func; // this is special function, provided by base I/O
-                   member.read_empty_stl_version = item.have_to_read_empty_stl_branch;
                 } else {
                    member.cntname = item_cnt.name;
                 }
@@ -2071,7 +2059,7 @@
                basket.fDisplacement = undefined;
 
             // rollback buffer - not needed in the future
-            buf.locate(buf.raw_shift);
+            // buf.locate(buf.raw_shift);
          }
 
          function ProcessBlobs(blobs) {
@@ -2097,8 +2085,6 @@
 
                bitems[k].bskt_obj = basket; // only number of entries in the basket are relevant for the moment
 
-               console.log('CHECK', basket.fKeylen, basket.fObjlen, basket.fNbytes);
-
                if (basket.fKeylen + basket.fObjlen === basket.fNbytes) {
                   // use data from original blob
                   buf.raw_shift = 0;
@@ -2117,11 +2103,7 @@
 
                bitems[k].raw = buf; // here already unpacket buffer
 
-               console.log('BUFFER', buf.remain());
-
                ReadBasketEntryOffset(bitems[k].branch, basket, buf);
-
-               console.log('Extract RAW ', buf.remain(), 'last', basket.fLast - basket.fKeylen, 'objlen', basket.fObjlen);
             }
 
             if (ExtractPlaces())