.

wcfs/internal/wcfs_virtmem.cpp

@@ -34,6 +34,7 @@ using namespace golang;
 #include <wendelin/bigfile/ram.h>
 #include <wendelin/bug.h>
 
+#include <algorithm>
 #include <string>
 #include <vector>
 
@@ -47,6 +48,7 @@ using namespace golang;
 #include "wcfs_misc.h"
 
 
+using std::min;
 using std::vector;
 
 typedef uint64_t Tid;
@@ -129,9 +131,9 @@ private:
 struct _File {
     Conn        *wconn;
     Oid         foid;       // hex of ZBigFile root object ID
-    size_t      blksize;    // block size of this file
+    size_t      blksize;    // block size of this file  XXX -> off_t ?
     os::File    headf;      // file object of head/file
-    // .headfsize    head/file size is known to be at least headfsize (size ↑=)
+    off_t       headfsize;  // head/file size is known to be at least headfsize (size ↑=)
 
     dict<int64_t, Tid>  pinned; // {} blk -> rev   that wcfs already sent us for this file
     vector<_Mapping*>   mmaps;  // []_Mapping ↑blk_start    mappings of this file
@@ -365,7 +367,6 @@ void Conn::_pin1(PinReq *req) {
 // XXX Conn::mmap
 
 // resync resyncs connection and its mappings onto different database view.
-#if 0
 error Conn::resync(Tid at) {
     Conn &wconn = *this;
     // XXX err ctx
@@ -374,24 +375,38 @@ error Conn::resync(Tid at) {
 
     for (auto fit : wconn._filetab) {
         Oid   foid = fit.first;
-        _File *f   = fit.second;
+        _File &f   = *fit.second;
 
         // XXX if file has no mappings and was not used during whole prev
         // cycle - forget and stop watching it
 
         // update f.headfsize and remmap to head/f zero regions that are now covered by head/f
         struct stat st;
-        auto err = f->headf.stat(&st) // XXX err
-        assert f.blksize == st.st_blksize    // blksize must not change
-        headfsize = st.st_size;
-        assert f.headfsize <= headfsize     // head/file size ↑=
-        assert headfsize % f.blksize == 0
-        for mmap in f.mmaps:
-            printf("  resync -> %s: unzero [%d:%d)" % (at, f.headfsize//f.blksize, headfsize//f.blksize));
-            memunzero = mmap.mem[f.headfsize - mmap.blk_start*f.blksize :
-                                 headfsize   - mmap.blk_start*f.blksize]
-            if len(memunzero) > 0:
-                mm.map_into_ro(memunzero, f.headf.fileno(), f.headfsize)
+        auto err = f.headf.stat(&st);
+        if (err != nil)
+            return err;
+
+        if ((size_t)st.st_blksize != f.blksize)     // blksize must not change
+            return fmt::errorf("wcfs bug: blksize changed: %zd -> %ld", f.blksize, st.st_blksize);
+        auto headfsize = st.st_size;
+        if (!(f.headfsize <= headfsize))   // head/file size ↑=
+            return fmt::errorf("wcfs bug: head/file size not ↑=");
+        if (!(headfsize % f.blksize == 0))
+            return fmt::errorf("wcfs bug: head/file size %% blksize != 0");
+
+        for (auto mmap : f.mmaps) {
+            printf("  resync -> %s: unzero [%lu:%lu)", h_(at), f.headfsize/f.blksize, headfsize/f.blksize);
+            uint8_t *mem_unzero_start = min(mmap->mem_stop,
+                            mmap->mem_start + (f.headfsize - mmap->blk_start*f.blksize));
+            uint8_t *mem_unzero_stop  = min(mmap->mem_stop,
+                            mmap->mem_start + (headfsize   - mmap->blk_start*f.blksize));
+
+            if (mem_unzero_stop - mem_unzero_start > 0) {
+                err = mm::map_into(mem_unzero_start, mem_unzero_stop-mem_unzero_start, PROT_READ, MAP_SHARED, f.headf, f.headfsize);
+                if (err != nil)
+                    return err;
+            }
+        }
 
         f.headfsize = headfsize;
 
@@ -405,8 +420,8 @@ error Conn::resync(Tid at) {
     }
 
     wconn.at = at;
+    return nil;
 }
-#endif
 
 // _remmapblk remmaps mapping memory for file[blk] to be viewing database as of @at state.
 //
@@ -444,8 +459,7 @@ error _Mapping::_remmapblk(int64_t blk, Tid at) {
     if (err != nil)
         return err;
     if ((size_t)st.st_blksize != f->blksize)
-        return fmt::errorf("wcfs bug: blksize changed: expected %lu; got %ld",
-                f->blksize, st.st_blksize);
+        return fmt::errorf("wcfs bug: blksize changed: %zd -> %ld", f->blksize, st.st_blksize);
 
     // block is beyond file size - mmap with zeros - else access to memory
     // after file.size will raise SIGBUS. (assumes head/f size ↑=)