On Tue, Apr 11, 2017 at 3:53 PM, Tom Lane <t...@sss.pgh.pa.us> wrote:
> Magnus Hagander <mag...@hagander.net> writes:
> > On Tue, Apr 11, 2017 at 3:19 PM, Tom Lane <t...@sss.pgh.pa.us> wrote:
> >> I think the patch is correct, but if there's any documentation of the
> >> walmethod APIs that would allow one to assert which side of the API got
> >> this wrong, I sure don't see it. Would it be unreasonable to insist
> >> on some documentation around that?
>
> > Would you say comments in the struct in walmethods.h is enough, or were
> you
> > thinking actual sgml docs when you commented that?
>
> This is just internal to pg_basebackup isn't it? I think comments in
> walmethods.h would be plenty.
>
Local to pg_basebackup and pg_receivewal, yes.
Something like the attached?
--
Magnus Hagander
Me: https://www.hagander.net/ <http://www.hagander.net/>
Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>
diff --git a/src/bin/pg_basebackup/walmethods.h b/src/bin/pg_basebackup/walmethods.h
index 8d679da..a3316a6 100644
--- a/src/bin/pg_basebackup/walmethods.h
+++ b/src/bin/pg_basebackup/walmethods.h
@@ -19,18 +19,50 @@ typedef enum
CLOSE_NO_RENAME
} WalCloseMethod;
+/*
+ * A WalWriteMethod structure represents the different methods used
+ * to write the streaming WAL as it's received.
+ *
+ * All methods that have a failure path will set errno on failure.
+ */
typedef struct WalWriteMethod WalWriteMethod;
struct WalWriteMethod
{
+ /* Open a target file. Returns Walfile, or NULL if open failed. */
Walfile(*open_for_write) (const char *pathname, const char *temp_suffix, size_t pad_to_size);
+
+ /*
+ * Close an open Walfile, using one or more methods for handling
+ * automatic unlinking etc. Returns 0 on success, other values
+ * for error.
+ */
int (*close) (Walfile f, WalCloseMethod method);
+
+ /* Check if a file exist */
bool (*existsfile) (const char *pathname);
+
+ /* Return the size of a file, or -1 on failure. */
ssize_t (*get_file_size) (const char *pathname);
+ /*
+ * Write count number of bytes to the file, and return the number
+ * of bytes actually written or -1 for error.
+ */
ssize_t (*write) (Walfile f, const void *buf, size_t count);
+
+ /* Return the current position in a file or -1 on error */
off_t (*get_current_pos) (Walfile f);
+
+ /*
+ * fsync the contents of the specified file. Returns 0 on
+ * success.
+ */
int (*sync) (Walfile f);
+
+ /* Clean up the Walmethod, closing any shared resources */
bool (*finish) (void);
+
+ /* Return a text for the last error in this Walfile */
char *(*getlasterror) (void);
};
--
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