.

wcfs/client/_wcfs.pyx

@@ -263,8 +263,6 @@ def _tpywlinkwrite(PyWatchLink pywlink, bytes pypkt):
 
 # pyerr converts error into python error.
 cdef object pyerr(error err):
-    if err == nil:
-        return None
     return pyerror.from_error(err)
 
 

wcfs/client/wcfs.cpp

@@ -79,7 +79,7 @@ static error mmap_into_ro(void *addr, size_t size, os::File f, off_t offset);
 // connect creates new Conn viewing WCFS state as of @at.
 pair<Conn, error> WCFS::connect(zodb::Tid at) {
     WCFS *wc = this;
-    xerr::Contextf E("connect @%s", v(at)); // XXX +wc path?
+    xerr::Contextf E("wcfs %s: connect @%s", v(wc->mountpoint), v(at));
 
     // TODO support !isolated mode
 
@@ -112,7 +112,6 @@ static global<error> errConnClosed = errors::New("connection closed");
 // opened fileh and mappings becomes invalid to use except close and unmap.
 error _Conn::close() {
     _Conn& wconn = *this;
-    //xerr::Contextf E("close conn @%s", v(wconn.at));
     xerr::Contextf E("wcfs %s: close conn @%s", v(wconn._wc->mountpoint), v(wconn.at));
     // XXX + conn # e.g. from wconn._wlink.id? or wlink.close should include its id itself?
 
@@ -296,7 +295,7 @@ error _Conn::__pin1(PinReq *req) {
 pair<FileH, error> _Conn::open(zodb::Oid foid) {
     _Conn& wconn = *this;
     error err;
-    xerr::Contextf E("conn @%s: open f<%s>", v(wconn.at), v(foid));
+    xerr::Contextf E("wcfs %s: conn @%s: open f<%s>", v(wconn._wc->mountpoint), v(wconn.at), v(foid));
 
     wconn._filehmu.lock();
     defer([&]() {
@@ -354,7 +353,7 @@ pair<FileH, error> _Conn::open(zodb::Oid foid) {
 error _FileH::close() {
     _FileH& fileh = *this;
     Conn    wconn = fileh.wconn;
-    xerr::Contextf E("conn @%s: close f<%s>", v(wconn->at), v(fileh.foid)); // XXX + wcfs path?
+    xerr::Contextf E("wcfs %s: conn @%s: close f<%s>", v(wconn->_wc->mountpoint), v(wconn->at), v(fileh.foid));
 
     // remove fileh from wconn._filehtab
     // fileh.close can be called several times and after first call another
@@ -373,8 +372,8 @@ error _FileH::close() {
 // If vma != nil, created mapping is associated with that vma of user-space virtual memory manager.
 pair<Mapping, error> _FileH::mmap(int64_t blk_start, int64_t blk_len, VMA *vma) {
     _FileH& f = *this;
-    xerr::Contextf E("conn @%s: mmap f<%s> [blk%ld +blk%ld)",
-            v(f.wconn->at), v(f.foid), blk_start, blk_len); // XXX +wcfs path?
+    xerr::Contextf E("wcfs %s: conn @%s: mmap f<%s> [blk%ld +blk%ld)",
+            v(f.wconn->_wc->mountpoint), v(f.wconn->at), v(f.foid), blk_start, blk_len);
 
     // XXX (blk_start + blk_len) * blk_size overflow
     error err;
@@ -432,7 +431,7 @@ pair<Mapping, error> _FileH::mmap(int64_t blk_start, int64_t blk_len, VMA *vma)
 // resync resyncs connection and its mappings onto different database view.
 error _Conn::resync(zodb::Tid at) {
     _Conn& wconn = *this;
-    xerr::Contextf E("conn @%s: resync -> @%s", v(wconn.at), v(at)); // XXX +wcfs path?
+    xerr::Contextf E("wcfs %s: conn @%s: resync -> @%s", v(wconn._wc->mountpoint), v(wconn.at), v(at));
 
     // XXX locking
     error err;
@@ -500,13 +499,13 @@ error _Conn::resync(zodb::Tid at) {
 // at=TidHead means unpin to head/ .
 // NOTE this does not check whether virtmem already mapped blk as RW.
 error _Mapping::_remmapblk(int64_t blk, zodb::Tid at) {
-    // XXX err context? blk #<blk> @<at>
     _Mapping *mmap = this;
-    xerr::Contextf E("conn @%s: f<%s>: remmapblk #%ld @%s",
-            v(mmap->fileh->wconn->at), v(mmap->fileh->foid), blk, v(at)); // XXX +wcfs path?
+    FileH f = mmap->fileh;
+    xerr::Contextf E("wcfs %s: conn @%s: f<%s>: remmapblk #%ld @%s",
+            v(f->wconn->_wc->mountpoint), v(f->wconn->at), v(f->foid), blk, v(at));
+
 
     ASSERT(mmap->blk_start <= blk && blk < mmap->blk_stop());
-    FileH f = mmap->fileh;
     error err;
 
     uint8_t *blkmem = mmap->mem_start + (blk - mmap->blk_start)*f->blksize;

wcfs/client/wcfs.h

@@ -42,14 +42,14 @@
 //      ───  ───── ──────────────────────────   ─────   /head/bigfile/X
 //
 // where @revR mmaps are being dynamically added/removed by this client package
-// to maintain X@at data view according to WCFS invalidation protocol(*).
+// to maintain X@at data view according to WCFS isolation protocol(*).
 //
 //
 // Integration with wendelin.core virtmem layer
 //
 // This client package can be used standalone, but additionally provides
 // integration with wendelin.core userspace virtual memory manager: when a
-// Mapping is created it can be associated as serving base layer for a
+// Mapping is created, it can be associated as serving base layer for a
 // particular virtmem VMA via FileH.mmap(vma=...). In that case, since virtmem
 // itself adds another layer of dirty pages over read-only base provided by
 // Mapping(+)
@@ -67,7 +67,7 @@
 //      ───  ───── ──────────────────────────   ─────   /head/bigfile/X
 //
 // the Mapping will interact with virtmem layer to coordinate
-// mapping memory updates.
+// updates to mapping virtual memory.
 //
 //
 // API overview
@@ -99,18 +99,9 @@
 #include <golang/libgolang.h>
 #include <golang/cxx.h>
 #include <golang/sync.h>
-using namespace golang;
-using cxx::dict;
-using cxx::set;
-
-#include <string>
-using std::string;
 
 #include <tuple>
-using std::tuple;
-
 #include <utility>
-using std::pair;
 
 #include "wcfs_misc.h"
 #include <wendelin/bug.h>
@@ -124,6 +115,13 @@ struct VMA;
 // wcfs::
 namespace wcfs {
 
+using namespace golang;
+using cxx::dict;
+using cxx::set;
+using std::tuple;
+using std::pair;
+
+
 typedef refptr<struct _Conn> Conn;
 typedef refptr<struct _Mapping> Mapping;
 typedef refptr<struct _FileH> FileH;
@@ -176,8 +174,8 @@ struct _Conn : object {
     sync::Mutex             _filehmu;
     dict<zodb::Oid, FileH>  _filehtab; // {} foid -> fileh
 
-    sync::WorkGroup _pinWG;
-    func<void()>    _pinCancel;
+    sync::WorkGroup _pinWG;     // pin/unpin messages from wcfs are served by _pinner
+    func<void()>    _pinCancel; // spawned under _pinWG.
 
     // don't new - create via WCFS.connect
 private:
@@ -203,7 +201,7 @@ private:
 //
 // The file view is maintained to be as of @Conn.at database state even in the
 // presence of simultaneous database changes. The file view uses
-// /head/<file>/data primarily and @revX/<file>/data pin overrides.
+// /head/<file>/data primarily and /@revX/<file>/data pin overrides.
 //
 // Use .mmap to map file view into memory.
 typedef refptr<struct _FileH> FileH;
@@ -231,6 +229,8 @@ public:
 };
 
 // Mapping represents one memory mapping of FileH.
+//
+// The mapped memory is [.mem_start, .mem_stop)
 typedef refptr<struct _Mapping> Mapping;
 struct _Mapping : object {
     FileH   fileh;