Date: Fri, 18 May 2012 15:21:57 -0400
From: Austin Clements <amdragon@MIT.EDU>
To: Jameson Graef Rollins <jrollins@finestructure.net>
Subject: Re: [PATCH v2 5/5] cli: lazily create the crypto gpg context only
	when needed
Message-ID: <20120518192157.GV11804@mit.edu>
References: <1337362357-31281-1-git-send-email-jrollins@finestructure.net>
	<1337362357-31281-2-git-send-email-jrollins@finestructure.net>
	<1337362357-31281-3-git-send-email-jrollins@finestructure.net>
	<1337362357-31281-4-git-send-email-jrollins@finestructure.net>
	<1337362357-31281-5-git-send-email-jrollins@finestructure.net>
	<1337362357-31281-6-git-send-email-jrollins@finestructure.net>
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Cc: Notmuch Mail <notmuch@notmuchmail.org>
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Quoth Jameson Graef Rollins on May 18 at 10:32 am:
> Move the creation of the crypto ctx into mime-node.c and create it
> only when needed.  This removes code duplication from notmuch-show and
> notmuch-reply, and should speed up these functions considerably if the
> crypto flags are provided but the messages don't have any
> cryptographic parts.
> ---
>  mime-node.c      |   25 +++++++++++++++++++++++++
>  notmuch-client.h |    3 ++-
>  notmuch-reply.c  |   19 -------------------
>  notmuch-show.c   |   23 -----------------------
>  4 files changed, 27 insertions(+), 43 deletions(-)
> 
> diff --git a/mime-node.c b/mime-node.c
> index 3adbe5a..592e0b6 100644
> --- a/mime-node.c
> +++ b/mime-node.c
> @@ -182,6 +182,31 @@ _mime_node_create (mime_node_t *parent, GMimeObject *part)
>  	return NULL;
>      }
>  
> +    /* Lazily create the gpgctx if it's needed and hasn't been initialized yet */
> +    if ((GMIME_IS_MULTIPART_ENCRYPTED (part) || GMIME_IS_MULTIPART_SIGNED (part))
> +	&& (node->ctx->crypto->verify || node->ctx->crypto->decrypt)) {
> +	if (!node->ctx->crypto->gpgctx) {

These if conditions could be combined, like

    if ((GMIME_IS_MULTIPART_ENCRYPTED (part) || GMIME_IS_MULTIPART_SIGNED (part))
	&& (node->ctx->crypto->verify || node->ctx->crypto->decrypt)
	&& !node->ctx->crypto->gpgctx) {

When I see two nested 'if's like this, I expect there to be an else
part to the inner if or something after the inner if (why else would
it be separate?) and then I wind up matching braces when I don't see
anything.  Also, one 'if' would save a level of indentation.

> +#ifdef GMIME_ATLEAST_26
> +	    /* TODO: GMimePasswordRequestFunc */
> +	    node->ctx->crypto->gpgctx = g_mime_gpg_context_new (NULL, "gpg");
> +#else
> +	    GMimeSession* session = g_object_new (g_mime_session_get_type(), NULL);
> +	    node->ctx->crypto->gpgctx = g_mime_gpg_context_new (session, "gpg");
> +	    g_object_unref (session);
> +#endif
> +	    if (node->ctx->crypto->gpgctx) {
> +		g_mime_gpg_context_set_always_trust ((GMimeGpgContext*) node->ctx->crypto->gpgctx, FALSE);
> +	    } else {
> +		/* If we fail to create the gpgctx set the verify and
> +		 * decrypt flags to FALSE so we don't try to do any
> +		 * further verification or decryption */
> +		node->ctx->crypto->verify = FALSE;
> +		node->ctx->crypto->decrypt = FALSE;
> +		fprintf (stderr, "Failed to construct gpg context.\n");
> +	    }
> +	}
> +    }
> +
>      /* Handle PGP/MIME parts */
>      if (GMIME_IS_MULTIPART_ENCRYPTED (part) && node->ctx->crypto->decrypt) {
>  	if (node->nchildren != 2) {
> diff --git a/notmuch-client.h b/notmuch-client.h
> index c671c13..c79eaa9 100644
> --- a/notmuch-client.h
> +++ b/notmuch-client.h
> @@ -348,7 +348,8 @@ struct mime_node {
>  /* Construct a new MIME node pointing to the root message part of
>   * message. If crypto->verify is true, signed child parts will be
>   * verified. If crypto->decrypt is true, encrypted child parts will be
> - * decrypted.
> + * decrypted.  The GPG context crypto->gpgctx does not need to be
> + * pre-initialized as it will be initialized lazily as needed.

Perhaps "If crypto->gpgctx is NULL, it will be lazily initialized."?
The variable does have to be "initialized", in the sense that it can't
be uninitialized data.

It's slightly awkward that it's the caller's responsibility to free
this lazily constructed object.  That should probably be documented.
We could more carefully reference count it, but I think that would
actually be worse because the reference count would probably bounce
through zero frequently.

>   *
>   * Return value:
>   *
> diff --git a/notmuch-reply.c b/notmuch-reply.c
> index 345be76..1a61aa7 100644
> --- a/notmuch-reply.c
> +++ b/notmuch-reply.c
> @@ -707,25 +707,6 @@ notmuch_reply_command (void *ctx, int argc, char *argv[])
>      else
>  	reply_format_func = notmuch_reply_format_default;
>  
> -    if (crypto.decrypt) {
> -#ifdef GMIME_ATLEAST_26
> -	/* TODO: GMimePasswordRequestFunc */
> -	crypto.gpgctx = g_mime_gpg_context_new (NULL, "gpg");
> -#else
> -	GMimeSession* session = g_object_new (g_mime_session_get_type(), NULL);
> -	crypto.gpgctx = g_mime_gpg_context_new (session, "gpg");
> -#endif
> -	if (crypto.gpgctx) {
> -	    g_mime_gpg_context_set_always_trust ((GMimeGpgContext*) crypto.gpgctx, FALSE);
> -	} else {
> -	    crypto.decrypt = FALSE;
> -	    fprintf (stderr, "Failed to construct gpg context.\n");
> -	}
> -#ifndef GMIME_ATLEAST_26
> -	g_object_unref (session);
> -#endif
> -    }
> -
>      config = notmuch_config_open (ctx, NULL, NULL);
>      if (config == NULL)
>  	return 1;
> diff --git a/notmuch-show.c b/notmuch-show.c
> index f4ee038..5f785d0 100644
> --- a/notmuch-show.c
> +++ b/notmuch-show.c
> @@ -1056,29 +1056,6 @@ notmuch_show_command (void *ctx, unused (int argc), unused (char *argv[]))
>  	break;
>      }
>  
> -    if (params.crypto.decrypt || params.crypto.verify) {
> -#ifdef GMIME_ATLEAST_26
> -	/* TODO: GMimePasswordRequestFunc */
> -	params.crypto.gpgctx = g_mime_gpg_context_new (NULL, "gpg");
> -#else
> -	GMimeSession* session = g_object_new (g_mime_session_get_type(), NULL);
> -	params.crypto.gpgctx = g_mime_gpg_context_new (session, "gpg");
> -#endif
> -	if (params.crypto.gpgctx) {
> -	    g_mime_gpg_context_set_always_trust ((GMimeGpgContext*) params.crypto.gpgctx, FALSE);
> -	} else {
> -	    /* If we fail to create the gpgctx set the verify and
> -	     * decrypt flags to FALSE so we don't try to do any
> -	     * further verification or decryption */
> -	    params.crypto.verify = FALSE;
> -	    params.crypto.decrypt = FALSE;
> -	    fprintf (stderr, "Failed to construct gpg context.\n");
> -	}
> -#ifndef GMIME_ATLEAST_26
> -	g_object_unref (session);
> -#endif
> -    }
> -
>      config = notmuch_config_open (ctx, NULL, NULL);
>      if (config == NULL)
>  	return 1;