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Add TOASTY_WRITE_CREATE_IF_MISSING flag for server-side file auto-creation

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Adds support for automatically creating files when write operations target
non-existent files. This is essential for REST PUT operations which should
be able to create new resources.

Implementation:
- Added TOASTY_WRITE_CREATE_IF_MISSING flag to ToastyFS API header
- Updated toasty_write() and toasty_begin_write() to accept flags parameter
- Client sends write flags in MESSAGE_TYPE_WRITE message to metadata server
- Metadata server parses flags and handles file auto-creation atomically:
  * When write fails with FILETREE_NOENT and flag is set
  * Logs creation to WAL for crash consistency
  * Creates file with default 4096-byte chunk size
  * Retries write with newly created file's generation tag
- Updated web proxy PUT handler to use TOASTY_WRITE_CREATE_IF_MISSING
- Updated examples and simulation client for new API signature

Benefits:
- Works for both sync and async APIs
- Single round trip (atomic server-side operation)
- Prevents race conditions
- Proper WAL logging ensures crash consistency
This commit is contained in:
Claude
2025-12-03 18:48:42 +00:00
parent a082f46b78
commit 8160c5ac51
9 changed files with 80 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/client.c
+7 -3
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@@ -124,6 +124,7 @@ typedef struct {
uint32_t num_chunks;
uint32_t chunk_size;
uint64_t expect_gen;
uint32_t flags; // Write operation flags (e.g., TOASTY_WRITE_CREATE_IF_MISSING)
UploadSchedule *uploads;
int num_uploads;
int cap_uploads;
@@ -744,7 +745,7 @@ unlock_and_exit:
ToastyHandle toasty_begin_write(ToastyFS *toasty,
ToastyString path, int off, void *src, int len,
ToastyVersionTag vtag)
ToastyVersionTag vtag, uint32_t flags)
{
int opidx = -1;
ToastyHandle handle = TOASTY_INVALID;
@@ -759,6 +760,7 @@ ToastyHandle toasty_begin_write(ToastyFS *toasty,
goto unlock_and_exit;
toasty->operations[opidx].path = path; // TODO: must be a copy
toasty->operations[opidx].flags = flags;
if (send_read_message(toasty, opidx, TAG_RETRIEVE_METADATA_FOR_WRITE, path, off, len, vtag) < 0) {
free_operation(toasty, opidx);
@@ -1974,6 +1976,7 @@ static void process_event_for_write(ToastyFS *toasty,
ToastyString path = toasty->operations[opidx].path;
uint32_t offset = toasty->operations[opidx].off;
uint32_t length = toasty->operations[opidx].len;
uint32_t flags = toasty->operations[opidx].flags;
if (path.len > UINT16_MAX) {
assert(0); // TODO
@@ -1984,6 +1987,7 @@ static void process_event_for_write(ToastyFS *toasty,
uint32_t num_chunks = num_upload_results;
message_write(&writer, &expect_gen, sizeof(expect_gen));
message_write(&writer, &flags, sizeof(flags));
message_write(&writer, &path_len, sizeof(path_len));
message_write(&writer, path.ptr, path.len);
message_write(&writer, &offset, sizeof(offset));
@@ -2449,9 +2453,9 @@ int toasty_read(ToastyFS *toasty, ToastyString path,
}
int toasty_write(ToastyFS *toasty, ToastyString path,
int off, void *src, int len, ToastyVersionTag *vtag)
int off, void *src, int len, ToastyVersionTag *vtag, uint32_t flags)
{
ToastyHandle handle = toasty_begin_write(toasty, path, off, src, len, vtag ? *vtag : 0);
ToastyHandle handle = toasty_begin_write(toasty, path, off, src, len, vtag ? *vtag : 0, flags);
if (handle == TOASTY_INVALID)
return -1;