[#BloombergLP-bdls-FilesystemUtil-sync]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdls.adoc[bdls]::xref:BloombergLP/bdls/FilesystemUtil.adoc[FilesystemUtil]::sync
:relfileprefix: ../../../
:mrdocs:

Synchronize mapped memory at `address` with the underlying file.

== Synopsis

Declared in `<bdls_filesystemutil.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
static
int
sync(
    char* address,
    std::size_t numBytes,
    bool syncFlag);
----

== Description

Synchronize the contents of the specified `numBytes` of mapped memory beginning at the specified `address` with the underlying file on disk. If the specified `syncFlag` is true, block until all writes to nonvolatile media have actually completed, otherwise, return once they have been scheduled. Return 0 on success, and a non‐zero value otherwise. The behavior is undefined unless `address` is aligned on a page boundary, `numBytes` is a multiple of `pageSize()`, and `0 <= numBytes`.

== Return Value

0 on success, and a non‐zero value otherwise

== Parameters

[cols="1,4"]
|===
| Name| Description
| *address*
| base address of the mapped memory to synchronize
| *numBytes*
| number of bytes to synchronize
| *syncFlag*
| `true` to block until writes complete; `false` to return once they have been scheduled
|===


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