Add binding for msync and associated constants

Author: jmert

docs/src/lib/public.md

@@ -11,6 +11,7 @@ The following functions are available on all Unix systems.
 UnixMmap.mmap
 UnixMmap.mincore
 UnixMmap.madvise!
+UnixMmap.msync!
 ```
 
 OS-specific constants for use with [`mmap`](@ref) and [`madvise!`](@ref) are defined at
@@ -30,6 +31,7 @@ import Main._flag_docs # hide
     <tr><td><code>MmapProtection</code></td>
         <td><code>MmapFlags</code></td>
         <td><code>AdviseFlags</code></td>
+        <td><code>SyncFlags</code></td>
     </tr>
     </thead>
     <tbody>
@@ -53,6 +55,13 @@ _flag_docs(UnixMmap.MmapFlags) # hide
 ```@example Linux
 _flag_docs(UnixMmap.AdviseFlags) # hide
 ```
+```@raw html
+            </td>
+            <td>
+```
+```@example Linux
+_flag_docs(UnixMmap.SyncFlags) # hide
+```
 ```@raw html
             </td>
         </tr>
@@ -72,6 +81,7 @@ import Main._flag_docs # hide
     <tr><td><code>MmapProtection</code></td>
         <td><code>MmapFlags</code></td>
         <td><code>AdviseFlags</code></td>
+        <td><code>SyncFlags</code></td>
     </tr>
     </thead>
     <tbody>
@@ -95,6 +105,13 @@ _flag_docs(UnixMmap.MmapFlags) # hide
 ```@example Apple
 _flag_docs(UnixMmap.AdviseFlags) # hide
 ```
+```@raw html
+            </td>
+            <td>
+```
+```@example Linux
+_flag_docs(UnixMmap.SyncFlags) # hide
+```
 ```@raw html
             </td>
         </tr>
@@ -114,6 +131,7 @@ import Main._flag_docs # hide
     <tr><td><code>MmapProtection</code></td>
         <td><code>MmapFlags</code></td>
         <td><code>AdviseFlags</code></td>
+        <td><code>SyncFlags</code></td>
     </tr>
     </thead>
     <tbody>
@@ -137,6 +155,13 @@ _flag_docs(UnixMmap.MmapFlags) # hide
 ```@example DragonFly
 _flag_docs(UnixMmap.AdviseFlags) # hide
 ```
+```@raw html
+            </td>
+            <td>
+```
+```@example Linux
+_flag_docs(UnixMmap.SyncFlags) # hide
+```
 ```@raw html
             </td>
         </tr>
@@ -156,6 +181,7 @@ import Main._flag_docs # hide
     <tr><td><code>MmapProtection</code></td>
         <td><code>MmapFlags</code></td>
         <td><code>AdviseFlags</code></td>
+        <td><code>SyncFlags</code></td>
     </tr>
     </thead>
     <tbody>
@@ -179,6 +205,13 @@ _flag_docs(UnixMmap.MmapFlags) # hide
 ```@example FreeBSD
 _flag_docs(UnixMmap.AdviseFlags) # hide
 ```
+```@raw html
+            </td>
+            <td>
+```
+```@example Linux
+_flag_docs(UnixMmap.SyncFlags) # hide
+```
 ```@raw html
             </td>
         </tr>
@@ -198,6 +231,7 @@ import Main._flag_docs # hide
     <tr><td><code>MmapProtection</code></td>
         <td><code>MmapFlags</code></td>
         <td><code>AdviseFlags</code></td>
+        <td><code>SyncFlags</code></td>
     </tr>
     </thead>
     <tbody>
@@ -221,6 +255,13 @@ _flag_docs(UnixMmap.MmapFlags) # hide
 ```@example NetBSD
 _flag_docs(UnixMmap.AdviseFlags) # hide
 ```
+```@raw html
+            </td>
+            <td>
+```
+```@example Linux
+_flag_docs(UnixMmap.SyncFlags) # hide
+```
 ```@raw html
             </td>
         </tr>
@@ -240,6 +281,7 @@ import Main._flag_docs # hide
     <tr><td><code>MmapProtection</code></td>
         <td><code>MmapFlags</code></td>
         <td><code>AdviseFlags</code></td>
+        <td><code>SyncFlags</code></td>
     </tr>
     </thead>
     <tbody>
@@ -263,6 +305,13 @@ _flag_docs(UnixMmap.MmapFlags) # hide
 ```@example OpenBSD
 _flag_docs(UnixMmap.AdviseFlags) # hide
 ```
+```@raw html
+            </td>
+            <td>
+```
+```@example Linux
+_flag_docs(UnixMmap.SyncFlags) # hide
+```
 ```@raw html
             </td>
         </tr>

src/consts.jl

@@ -9,6 +9,13 @@ import .Sys # explicitly imported to allow docs generation to override
 end
 Base.cconvert(::Type{T}, pf::MmapProtection) where {T <: Integer} = T(pf)
 
+@bitflag SyncFlags::Cuint begin
+    MS_ASYNC      = 0x1
+    MS_INVALIDATE = 0x2
+    MS_SYNC       = 0x4
+end
+Base.cconvert(::Type{T}, sf::SyncFlags) where {T <: Integer} = T(sf)
+
 @staticexpand @bitflag MmapFlags::Cuint begin
     MAP_FILE      = 0x00
     MAP_SHARED    = 0x01
@@ -134,10 +141,22 @@ let _flag_docs
     ```
     """ MmapProtection
 
+    @doc """
+        @bitflag UnixMmap.SyncFlags
+
+    Set of bit flags which control the memory synchronization behavior.
+
+    The flags available on $(Sys.KERNEL) are:
+    ```julia
+    $(_flag_docs(SyncFlags))
+    ```
+    """ SyncFlags
+
+
     @doc """
         @bitflag UnixMmap.MmapFlags
 
-    Set of bit flags which control the handling of the memory mappged region. The flag
+    Set of bit flags which control the handling of the memory mapped region. The flag
     should be a bitwise-or combination of flags.
 
     The flags available on $(Sys.KERNEL) are:

src/mmap.jl

@@ -281,3 +281,18 @@ function madvise!(array::Array, flag::AdviseFlags = MADV_NORMAL)
     end
     return array
 end
+
+"""
+    msync!(array, flag::SyncFlags = MS_SYNC)
+
+Synchronizes the memory-mapped `array` and its backing file on disk.
+"""
+function msync!(array::Array, flag::SyncFlags = MS_SYNC)
+    GC.@preserve array begin
+        ptr, off, len = pagepointer(array)
+        Base.systemerror("msync",
+                ccall(:msync, Cint, (Ptr{Cvoid}, Csize_t, Cint),
+                      ptr, len, flag) != 0)
+    end
+    return array
+end

test/runtests.jl

@@ -196,3 +196,13 @@ end
     A = mmap(Array{Int}, 500)
     @test A == UnixMmap.madvise!(A, UnixMmap.MADV_WILLNEED)
 end
+
+@testset "Synchronizing" begin
+    # It's hard to test behavior of the sync flags --- just check for not erroring
+    mktemp() do path, io
+        A = mmap(io, Array{Int}, 500)
+        @test A == UnixMmap.msync!(A, UnixMmap.MS_SYNC | UnixMmap.MS_INVALIDATE)
+        A[:] .= 1.0
+        @test A == UnixMmap.msync!(A, UnixMmap.MS_ASYNC)
+    end
+end