[lttng-dev] [Patch LTTng-tools 4/4] Dump a named metadata only once per session

[Mathieu Desnoyers]

----- Original Message -----
> From: "Geneviève Bastien" <gbastien+lttng at versatic.net>
> To: lttng-dev at lists.lttng.org
> Sent: Friday, January 24, 2014 3:07:25 PM
> Subject: [lttng-dev] [Patch LTTng-tools 4/4] Dump a named metadata only once	per session
> 
> Named metadata can be used more than once in a single tracepoint, or many

(global types ?)

This is adding a linked-list (O(n)) on something that can be called
quite often. It will not scale if there are many enums in a process.
This should be changed into a hash table.


> tracepoints can use it. It must be statedumped only once in a given session.
> 
> Signed-off-by: Geneviève Bastien <gbastien+lttng at versatic.net>
> ---
>  src/bin/lttng-sessiond/ust-metadata.c | 39
>  +++++++++++++++++++++++++++++++++++
>  src/bin/lttng-sessiond/ust-registry.c | 11 ++++++++++
>  src/bin/lttng-sessiond/ust-registry.h |  8 +++++++
>  3 files changed, 58 insertions(+)
> 
> diff --git a/src/bin/lttng-sessiond/ust-metadata.c
> b/src/bin/lttng-sessiond/ust-metadata.c
> index 87d21fc..8b904a8 100644
> --- a/src/bin/lttng-sessiond/ust-metadata.c
> +++ b/src/bin/lttng-sessiond/ust-metadata.c
> @@ -316,6 +316,27 @@ int _lttng_one_metadata_statedump(struct
> ust_registry_session *session,
>  {
>  	int ret = 0, i;
>  
> +	/* Check if the metadata was already dumped */
> +	if (session->dumped_named_metadata != 0) {
> +		struct ust_dumped_metadata *dumped = session->dumped_named_metadata;
> +		char *metadata_name;

missing newline.

Thanks,

Mathieu

> +		switch (metadata->mtype) {
> +		case ustctl_mtype_enum:
> +			metadata_name = metadata->u.ctf_enum.name;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +		do {
> +			if (dumped->mtype == metadata->mtype) {
> +				if (strcmp(dumped->name, metadata_name) == 0) {
> +					return 0;
> +				}
> +			}
> +			dumped = dumped->next;
> +		} while (dumped);
> +	}
> +
>  	switch (metadata->mtype) {
>  	case ustctl_mtype_enum:
>  	{
> @@ -362,6 +383,24 @@ int _lttng_one_metadata_statedump(struct
> ust_registry_session *session,
>  		return -EINVAL;
>  	}
>  
> +	/* Flag this metadata as dumped */
> +	struct ust_dumped_metadata *dumped;
> +	dumped = zmalloc(sizeof(*dumped));
> +	if (!dumped) {
> +		ret = -ENOMEM;
> +		return ret;
> +	}
> +	dumped->mtype = metadata->mtype;
> +	switch (metadata->mtype) {
> +	case ustctl_mtype_enum:
> +		strncpy(dumped->name, metadata->u.ctf_enum.name, LTTNG_UST_SYM_NAME_LEN);
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +	dumped->next = session->dumped_named_metadata;
> +	session->dumped_named_metadata = dumped;
> +
>  	return ret;
>  }
>  
> diff --git a/src/bin/lttng-sessiond/ust-registry.c
> b/src/bin/lttng-sessiond/ust-registry.c
> index 00e1c26..25cd31d 100644
> --- a/src/bin/lttng-sessiond/ust-registry.c
> +++ b/src/bin/lttng-sessiond/ust-registry.c
> @@ -568,6 +568,7 @@ int ust_registry_session_init(struct ust_registry_session
> **sessionp,
>  	session->uint64_t_alignment = uint64_t_alignment;
>  	session->long_alignment = long_alignment;
>  	session->byte_order = byte_order;
> +	session->dumped_named_metadata = 0;
>  
>  	session->channels = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
>  	if (!session->channels) {
> @@ -630,4 +631,14 @@ void ust_registry_session_destroy(struct
> ust_registry_session *reg)
>  	}
>  
>  	free(reg->metadata);
> +
> +	/* Free all dumped metadata */
> +	if (reg->dumped_named_metadata) {
> +		struct ust_dumped_metadata *dumped;
> +		do {
> +			dumped = reg->dumped_named_metadata;
> +			reg->dumped_named_metadata = dumped->next;
> +			free(dumped);
> +		} while (reg->dumped_named_metadata);
> +	}
>  }
> diff --git a/src/bin/lttng-sessiond/ust-registry.h
> b/src/bin/lttng-sessiond/ust-registry.h
> index 183db0f..a6c7e6e 100644
> --- a/src/bin/lttng-sessiond/ust-registry.h
> +++ b/src/bin/lttng-sessiond/ust-registry.h
> @@ -31,6 +31,12 @@
>  
>  struct ust_app;
>  
> +struct ust_dumped_metadata {
> +	enum ustctl_metadata_types mtype;
> +	char name[LTTNG_UST_SYM_NAME_LEN];
> +	struct ust_dumped_metadata *next;
> +};
> +
>  struct ust_registry_session {
>  	/*
>  	 * With multiple writers and readers, use this lock to access the registry.
> @@ -75,6 +81,8 @@ struct ust_registry_session {
>  	 * deletes its sessions.
>  	 */
>  	unsigned int metadata_closed;
> +	/* The list of named metadata already dumped */
> +	struct ust_dumped_metadata *dumped_named_metadata;
>  };
>  
>  struct ust_registry_channel {
> --
> 1.8.5.3
> 
> 
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> 

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com